Rayane El Sibai
email: rayane.elsibai@mu.edu.lb

Jacques Bou Abdo
email: jbouabdo@ndu.edu.lb

Chady Abou
email: chady.aboujaoude@ua.edu.lb

Jacques Demerjian
email: jacques.demerjian@ul.edu.lb

Yousra Chabchoub
email: yousra.chabchoub@isep.fr

Raja Chiky
email: raja.chiky@isep.fr

A cloud-based foundational infrastructure for water management ecosystem

Keywords: Cloud computing, data streams, data quality, sampling techniques, Software as a Service (SaaS)

Water monitoring is one of the critical battles of sustainability for a better future of humanity. 44 countries are considered at high risk of the water crisis, 28 of which are developing countries and have limited capacity to deploy a national scale solution. As a response to the United Nation's sustainability goals and initiatives, this paper proposes an intelligent water monitoring service which acts as a foundational infrastructure for all future water management systems. It also provides municipalities, Non-Governmental Organization and other private initiatives with the tools needed to establish local water monitoring in the scale of villages or rural areas with a very small initial investment.

I. INTRODUCTION

In 2015, the United Nations General Assembly approved the following: "Transforming our world: the 2030 Agenda for Sustainable Development" [START_REF] Un Desa | Transforming our world: The 2030 agenda for sustainable development[END_REF]. In order to guide the actions of the international community towards global sustainability, several objectives related to resource management and its consequence were defined. The water-related goals were the following: (1) Eradicate hunger, ensure food security and nutrition, and promote sustainable agriculture (2) Ensure the availability and sustainable management of water and sanitation for everyone, and finally, (3) Protect, restore and improve the sustainable use of terrestrial ecosystems, manage forests sustainably, combat desertification, etc.

ICT solutions for water management have become extremely important as a global initiative. Intelligent water management systems [START_REF] Eustace M Dogo | Blockchain and internet of things-based technologies for intelligent water management system[END_REF], dynamic water pricing systems [START_REF] Grigoras | Ict based smart management solution to realize water and energy savings through energy efficiency measures in water distribution systems[END_REF], peer-to-peer water trading systems [START_REF] Seung | A simple blockchainbased peer-to-peer water trading system leveraging smart contracts[END_REF], and e-agriculture [START_REF] Lin | Blockchain: The evolutionary next step for ict e-agriculture[END_REF] are at the core of UN's sustainability goals and are becoming very hot research topics. The development of efficient ICT solutions for water management relies on continuous updates of accurate and timely information, but the literature is short on water monitoring systems specialized in providing such information. It is inefficient and impractical to require every ICT solution to collect and process massive streams of data as a prerequisite to performing its task. The overhead resulting from adding a water monitoring component to every water management system is simply too expensive.

In this work, we are interested in designing an intelligent water monitoring service that helps in complementing the water management ecosystem and facilitates the development of ICT solutions for water management. The designed service collects, processes and delivers accurate, meaningful, timely, dynamic, and cost-efficient data, through standardized interfaces, to the systems needing it, as shown in Figure 1.

To do so, we propose a new cloud service that offloads the complexity of the central monitoring system with all its overheads to the cloud. These overheads include huge initial investment which could prevent NGOs and private initiatives from deploying a functional monitoring system, scalability issues, and maintenance issues. This service supports new business models and an ecosystem that can be created around the generated data while providing water network operators with a plethora of tools to make their decisions smarter, faster, or automatic. Artificial Intelligence can be designed to utilize standardized interfaces. The standardized interface is fundamental for the cloud computing ecosystem. It provides end-users with the capability to access cloud services. Analytics tools, big data applications, security management, and monitoring tools are among the commonly provided services. In the rest of this paper, we refer to Intelligent water management systems, dynamic water pricing systems, peer-to-peer water trading systems, and e-agriculture by water management systems.

The rest of the paper is organized as follows. Section II Fig. 1: Water management ecosystem.

presents the related works. Section III discusses the requirements for a functional central monitoring system. Section IV introduces our contribution, the "Native Filtering as a Service (NFaaS)". The paper ends with a conclusion.

II. RELATED WORKS

Cloud computing for environmental monitoring consists of using cloud infrastructure to control the data streams generated by Wireless Sensor Networks (WSNs). The adoption of cloud technology allows users and businesses to save time and costs since the cost of storage and the efforts of the infrastructure installation, configuration, and maintenance drops dramatically and become negligible. In addition, the estimation and planning of the required resources, and the use of excessive storage and computation capacities are no longer required as the resources can be flexibly adjusted as needed.

In [START_REF] Prathibha | A real-time system for environmental study based on cloud computing[END_REF], a cloud-based system has been proposed to monitor the changes that occurred in the environment. The system generates an alert and notifies the user when an anomaly is detected. The main benefit of this system is to reduce the amount of time needed to retrieve and analyze the data when compared to the traditional data analysis systems. [START_REF] Kanagaraj | Cloud-based remote environmental monitoring system with distributed wsn weather stations[END_REF] presented a cloud-based system for weather monitoring. It is composed of two layers: an interface layer to allow the interaction between the users and the cloud through a web server, and a database layer to allow storing and fetching the data coming from the WSNs base stations. [START_REF] Arroyo | Wireless sensor network combined with cloud computing for air quality monitoring[END_REF] implemented a cloud system to store, process, and monitor the data related to the air quality and detect specific compounds and contaminants. Several parameters related to the air are observed and sent to the cloud by the sensors. [START_REF] Yue Shan | Big data platform for air quality analysis and prediction[END_REF] designed a semantic Extract-Transform-Load (ETL) framework on the cloud platform for monitoring and predicting air quality. At first, different data analysis techniques are applied to clean the data and remove duplicated values. Secondly, a semantic model is built so that to have a significant relationship between the data. Finally, several data mining algorithms are used to analyze and predict air quality.

A framework based on blockchain technology for dynamic water pricing has been proposed by [START_REF] Grigoras | Ict based smart management solution to realize water and energy savings through energy efficiency measures in water distribution systems[END_REF], in which the water price is a function of the energy prices, which drops as the price of the energy required to pump the water drops. The deployment of water management systems in African countries requires several specifications such as continuous monitoring, remote control of water distribution, etc. The impact of using blockchain on intelligent water management systems in these areas was investigated by [START_REF] Eustace M Dogo | Blockchain and internet of things-based technologies for intelligent water management system[END_REF]. In [START_REF] Asit | Integrated water resources management: a reassessment: a water forum contribution[END_REF], the authors concluded that it is difficult to deploy an Integrated Water Resources Management (IWRM) in real life. The required monitoring, management, and maintenance operations, on a national scale, required are very expensive.

III. CENTRAL MONITORING SYSTEM REQUIREMENTS

In this section, we show the infrastructure requirements for a functional central monitoring system as calculated in our previous work [START_REF] Sibai | Information technology infrastructure for data streams native filtering[END_REF]. As will be shown, these requirements can be an obstacle facing the deployment of a water monitoring system by states, municipalities, NGOs, or private initiatives in developing nations, who are in desperate need of such a system.

The calculated infrastructure includes the computational resources required to run the central monitoring system which is responsible for data cleaning and summarization, and the number of servers needed to ensure high availability of the service. The used dataset is issued from the water sensors deployed in the Paris region. The recorded data are structured data streams that have both spatial and temporal characteristics. Each record observation is composed of two fields: the recording date of the measure, and the value of the measure (water consumption volume). These data are regularly generated by the sensors with a frequency of one observation every 15 minutes. The specifications of our server on which we run the central monitoring system are the following: RAM: 4 GB, System Disk: 120 GB, and Processor: 2.7 GHz Intel Core i5 -8305G. We evaluate in Figure 2 the response time taken by the central monitoring system to construct a summary for each received data stream, using the sampling algorithms previously discussed. One can notice that the response time increases linearly with the increase of the number of streams to be processed. The following equation stands for the response time of the sampling filter as a function of the number of streams to be processed:

Response time = a × N umber of streams + b (1)
where b is a fixed amount of time needed to initialize the sampling filter, and a×N umber of streams is an incremental component proportional to the number of received data streams. This is due to the collision problem that it suffers, and the number of data to be written in the summary, which is higher compared to that of other sampling algorithms [START_REF] Sibai | Information technology infrastructure for data streams native filtering[END_REF]. Notice that the size of the window has a high impact on the execution time taken by Chain-sample. This time increases as the window size increases, as demonstrated in [START_REF] Sibai | A performance study of the chain sampling algorithm[END_REF]. The figure also shows that the Deterministic sampling algorithm has the smallest execution time, as it is the simplest sampling method.

Figure 3 represents the cleaning process's response time. One can conclude that the cleaning time needed is not linearly dependent on the number of received streams. In fact, for a single data stream, this cleaning time depends on the following parameters: the number of received observations, the amount and the distribution of missing data and outliers. As these parameters vary widely from one stream to another, the cleaning time cannot be predicted in advance.

2) Service availability: Increasing the availability of a system involves maximizing the percentage of time during which the system is operational. To protect the system against unexpected overloads and to avoid the system balancing can be used to ensure high availability. It consists of using a set of servers in which the incoming streams are evenly distributed to help reduce the load on a single server. We show in Figure 4 the calculated number of servers needed to run the central monitoring system while ensuring high availability for the stream rates discussed above. As shown in Figure 4, a local small-scale monitoring system of 1 million sensors requires a data center of 253 to 337 servers for stream cleaning and processing. This data center is too expensive for private initiatives, NGOs, or municipalities to install, operate, and maintain thus jeopardize their willingness to deploy such a critical system. Consequently, water management systems relying on the data generated from the monitoring system will be jeopardized as well.

IV. NATIVE FILTERING AS A SERVICE (NFAAS)

To provide states, municipalities, NGOs, or private initiatives the possibility to deploy a water management system without the burdens of water monitoring systems, we propose a new cloud service called Native Filtering as a Service, which is presented in this section. Sensor data streams are arriving at a high-speed. They produce a huge mass of data, impossible to store entirely in due time. On their side, erroneous, inaccurate, or inconsistent data cause much damage as for the supervision and detection of abnormal phenomena in the monitored network. It is, therefore, necessary to filter these data on the fly and to store only those that are relevant by producing summaries. Native filtering consists of filtering qualitatively and quantitatively, in real-time, the received sensor data to overcome the poor data quality and huge data volume problems.

The native filtering process consists of two sub-processes: the cleaning filter, also called a qualitative filter, and the sampling filter, also called a quantitative filter. When the qualitative filter receives the data from the sensors, it proceeds to check and to improve their quality. Thereafter, the data are summarized by the quantitative filter. Native Filtering as a Service (NFaaS) consists of providing the cleaning and sampling filters as services via cloud computing. Therefore, clients can access and benefit from the cleaning and sampling applications over the Internet, on-demand, with a payment based on their use. Once the data are clean and summarized, it is essential to store them, so that they are available for future analysis either by their owners or by other users interested in these data. Eventually, the visualization of the obtained data analysis results is essential to help the network explorer to understand the monitored environment. That is where the Big Data as a Service (BDaaS) comes in.

BDaaS provides the users with a remote cloud storage server to store and edit their summaries, as well as an analytics platform for the analysis of these summaries and the visualization of the results. The cloud-based sensors data streams processing flow is shown in Figure 5. Every instance of NFaaS has its own geographical coverage, specialized analytics, and scope. Water management systems may be interested in retrieving data from multiple NFaaS instances or consortiums. Multiple NFaaS instances can store their output on a consortium blockchain, as shown in Figure 5, and this provides endless options for an ecosystem of brokers, regulators, investors, and innovators.

A. Overview of native filtering services

The native filter takes as input several data streams, issued from the sensors in their native format, and gives in output new data streams in the same format. It consists of two subfilters: the qualitative filter (Cleaning as a Service) to clean the data by detecting and deleting errors and duplicated data and predicting missing and erroneous data, and the quantitative filter (Sampling as a Service) which is responsible for reducing the large volume of data by using several sampling algorithms. Our approach for managing the data stream quality is to first evaluate the data quality according to several dimensions, and then, improve it to obtain reliable and effective data analysis results. Since data streams are volatile, once expired, they are no longer available for analysis. Therefore, all the needed queries have to be defined before the arrival of data streams.

However, new requirements may appear after the arrival of the stream. In this case, the data stream management system cannot answer new queries. One of the solutions to palliate this problem is to store an extract of the stream in a compact structure, called summary. The cleaning and sampling services will be discussed in Section IV-B.

In figure 6, we show the use case diagram for NFaaS cloud service. The class diagram of the native filtering services is presented in Figure 7.

B. Services explanation

Data analysis results depend on data quality. Sensors data are often of bad quality. Since the conclusions and decisions that the network explorer will take are based on the data, this can lead to erroneous results and faulty decisions. One solution to deal with this problem is to use sensors with high precision and to deploy redundant sensors to cover the breakdown of a given sensor. Nevertheless, this approach is very expensive as it requires very high costs for the sensors. That is why we opted for a software-based solution where the data quality is evaluated and improved using several complementary methods. Our solution is based on the Total Data Quality Management (TDQM) methodology [START_REF] Richard | A product perspective on total data quality management[END_REF]. At first, data quality dimensions are defined and measured. Then, a set of quantitative metrics are produced. Finally, several actions are taken to enhance data quality.

Data quality metrics we are dealing with are the accuracy, completeness, reliability, and confidence. These dimensions are chosen because of their important impact on the data analysis results. The accuracy dimension represents the point at which the sensor readings are close to the real observations. In sensor networks, sensor readings may deviate from the real observations due to several factors such as the physical sensor failure, sensor malfunction, etc. Data accuracy can be improved by detecting and removing these erroneous data.

Errors are of three types: outliers, spikes, and stuck-at. Stuckat errors can be detected using the CUSUM algorithm that we proposed previously [START_REF] Sibai | An in-depth analysis of cusum algorithm for the detection of mean and variability deviation in time series[END_REF]. Outliers and spikes errors are detected using a set of static rules. In the context of the water distribution network, any reading value that exceeds the maximum theoretical flow value (called debit M ax) that a sensor can emit will be considered as an outlier. The debitM ax value is calculated using the Hazen-Williams formula. This latter determines the maximum transportable flow rate through a given pipe according to the physical properties of the pipe and the pressure drop caused by the friction of the used material. The debitM ax value is calculated according to the Hazen-Williams formula, where DH is the altitude difference between the two extremities of the pipe, in meters, L is the length of the pipe, in meters, C is the friction coefficient of the used material, and D is the diameter of the pipe, in meters. The accuracy degree for each sensor reading takes the following values: 0 if the value is erroneous, otherwise, 1. The debitM ax value is calculated as follows: The completeness dimension depends on the frequency for recording the data in the environment and the frequency for communicating the recorded observations to the data center or the server. Based on the known stream arrival rate, the amount of missing data at each instant t (in hour) can be computed as follows:

debitM ax = 0.28 × ((DH/L) 0.54 ) × (C × D) 2.63 m 3 /sec (2)
cumulativeM issing t = [ t t0 N umber of missing data (t -t 0 ) × streamRate ] (3)
The sensor reliability dimension is based on the accuracy dimension. It is measured by the cumulativeError degree The confidence dimension depicts the degree of trustiness of the sensor reading. This degree depends on the originality of the data. When a value is missing or erroneous, it has to be regenerated to enhance its quality. In this case, its conf idence degree is the proportion of consecutive missing or erroneous values around it. x is calculated relative to a given time period as follows, where m is the number of consecutive missing values, IAD is the Interpolation Allowed Duration (in hours) representing the maximum missing data period allowed to replace the data.

conf idence = [1 - m IAD × streamRate ] (5)
Once the quality dimensions are evaluated, the cleaning filter proceeds to enhance data quality by deleting erroneous and duplicated data and replacing erroneous and missing data. The native filtering solution uses sampling algorithms to summarize the data and construct a summary. The singularity of this structure lies in its ability to perform various data analysis tasks on the stream and to answer in an approximate way to any request, whatever the period of time investigated. Different sampling algorithms can be applied by the native filtering solution. The choice of the sampling technique depends on the required precision regarding the data analysis results, and the constraints related to the processing time needed by the algorithm. Four sampling methods were implemented in the sampling filter: Simple Random Sampling (SRS), Deterministic sampling, Reservoir sampling, and Chain-sample. More details about these algorithms can be found in [START_REF] Sibai | A performance evaluation of data streams sampling algorithms over a sliding window[END_REF].

C. Big Data as a Service (BDaaS) in standardized interfaces

The built summaries from the NFaaS are sources of BDaaS. They can be published on the cloud allowing their owners to get a return on investment. Data is a valuable asset for every organization. The intelligent use of data can help make decisions based on real facts, and thus, improve the business processes by minimizing the risks and increasing the business in general. The concept of DaaS is that the data, regardless of its source and type, can be cleaned, enriched, integrated into a centralized infrastructure, and made available to different users and applications on the cloud. In this way, DaaS allows the users to obtain the appropriate data and to use it directly to meet their needs, and the data owners to get a return on investment.

Data can be used and analyzed to improve the performance of systems and decision support applications, as well as for risk assessment. While the benefits of Big Data are significant, many challenges remain. They are related to the high volume of the data, their velocity, confidentiality, and variety. Big Data analysis involves several distinct tasks such as data acquisition, data analysis, and data modeling. The use of the cloud environment for processing Big Data is an ideal solution, both scalable and adapted to huge data volume. In our monitoring system, data analytic tools can be used in detecting abnormal phenomena such as micro-variations of certain parameters that have an impact in terms of risk, variation, or non-nominal frequency, etc, as soon as possible, thus, allowing to save considerable amounts of potable water. Finally, data visualization is essential for interpreting the data. Cloud computing provides users and businesses with visualization tools. It allows them to spend their time in visualizing their data without having to worry about the infrastructure.

V. CONCLUSION

Water monitoring is a critical challenge for humankind since we share the same globe, breath the same air, drink the same water, and share the same DNA. We are not short on solutions, but we are in desperate need of practical ones that are implementable in developing countries and rural areas. Successful solutions are not necessarily the most technically advanced, but the ones with successful business models. In this paper, we proposed a water monitoring cloud service that facilitates the development of critically needed water management systems. The strength of this proposal is multifolded. First, it doesn't rely on the government's maintenance which can be very inefficient in developing countries. The second strength is that it creates an ecosystem around the generated data which can help develop the areas using these services

1 )

 1 Response time: The execution time of the sampling process includes the time of reading, sampling, and writing the data in the summary, and is dependent on the following factors: (1) Number of received observations for each stream, which depends on the stream rate or frequency of the sensor, (2) Number of streams received simultaneously, (3) Sampling rate, (4) Window size, and (5) Sampling technique.

Fig. 2 :

 2 Fig. 2: Execution time of the sampling process according to the number of streams, locally.

Figure 2

 2 Figure2also shows that the Chain-sample algorithm has the highest execution time compared to other sampling algorithms. This is due to the collision problem that it suffers, and the number of data to be written in the summary, which is higher compared to that of other sampling algorithms[START_REF] Sibai | Information technology infrastructure for data streams native filtering[END_REF]. Notice that the size of the window has a high impact on the execution time taken by Chain-sample. This time increases as the window size increases, as demonstrated in[START_REF] Sibai | A performance study of the chain sampling algorithm[END_REF]. The figure also shows that the Deterministic sampling algorithm has the smallest execution time, as it is the simplest sampling method.

Fig. 3 :

 3 Fig. 3: Response time of the cleaning process according to the number of streams.

Fig. 4 :

 4 Fig. 4: Required number of servers to ensure high availability.

Fig. 5 :Fig. 6 :

 56 Fig. 5: Cloud-based sensors data streams processing.

Fig. 7 :

 7 Fig. 7: Class diagram of the Native filtering services.

https://www.waves-rsp.org

ACKNOWLEDGMENT

This work was funded by the FUI 17 project WAVES 1 . The project aims to design and develop a monitoring platform for the supervision of water distribution networks. The goal is to develop a relevant solution for the realization of a decision support system for the network operators and explorers.


Laurent Marivaux
email: laurent.marivaux@umontpellier.fr

Walter Aguirre-Diaz

Aldo Benites-Palomino

Guillaume Billet

Myriam Boivin

François Pujos

Rodolfo Salas-Gismondi

Julia V Tejada-Lara

Rafael M Varas-Malca

Pierre-Olivier Antoine

Ruiz Leal

Masanaru Takai

Richard F Kay

Jonathan M G Perry

New record of Neosaimiri (Cebidae, Platyrrhini) from the late Middle Miocene of Peruvian Amazonia

Keywords: Primates, Tropical South America, Peru, Neogene, Laventan, Paleobiogeography

The Honda Group of La Venta, Colombia, has yielded a wide array of crown platyrrhine primates, documenting the late Middle Miocene epoch (ca. 13.1-12.6 Ma, Laventan South American Land Mammal Age). Although exceptional, this record represents only a snapshot of the evolutionary history of New World monkeys because virtually none of the primate taxa recorded at La Venta had so far been found elsewhere. We describe here few dental remains of a cebine platyrrhine discovered from Laventan deposits in the San Martín Department of Peru (Peruvian Amazonia). The primate dental specimens from that new fossil-bearing locality (TAR-31) are strongly reminiscent morphologically of the teeth of Neosaimiri fieldsi from La Venta. However, given that several aspects of the dental variability from TAR-31 are unknown, we prefer to provide an assignment with open nomenclature (i.e., Neosaimiri cf. fieldsi), instead of formally referring these remains to N. fieldsi, pending the discovery of additional specimens. The occurrence of Neosaimiri in Peru, in coeval deposits of La Venta, thus represents a second and southernmost record of that low-latitude genus in the Neotropics, thereby demonstrating its wide distribution along the northwestern edge of the Pebas Mega-Wetland System, in tropical western South America.

Paleontological investigations in Peruvian Amazonia are carried out in the framework of an ongoing collaboration agreement between the Museo de Historia Natural de la Universidad Nacional Mayor San Marcos (Lima, Peru) and the Institut des Sciences de l'Évolution de Montpellier-Université de Montpellier, France. This is ISE-M publication 2020-111 Sud.

Introduction

The fossil record of primates from tropical South America is primarily documented by the famous late Middle Miocene outcrops of La Venta (Honda Group) in Colombia, which have yielded a wide array of crown platyrrhines (e.g., [START_REF] Stirton | A new monkey from the La Venta Miocene of Colombia[END_REF][START_REF] Stirton | Ceboid monkeys from the Miocene of Colombia[END_REF][START_REF] Setoguchi | Kondous laventicus, a new ceboid primate from the Miocene of La Venta, Colombia, South America[END_REF][START_REF] Setoguchi | Kondous laventicus, a new ceboid primate from the Miocene of La Venta, Colombia, South America[END_REF]Rosenberger, 1985, 1987;[START_REF] Luchterhand | Mohanamico hershkovitzi, gen. et sp. nov., un primate du Miocène moyen d'Amérique du Sud[END_REF][START_REF] Kay | Stirtonia victoriae, a new species of Miocene Colombian primate[END_REF][START_REF] Rosenberger | Laventiana annectens, new genus and species: fossil evidence for the origins of callitrichine New World monkeys[END_REF][START_REF] Kay | Giant" tamarin from the Miocene of Colombia[END_REF][START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF][START_REF] Fleagle | Fossil New World monkeys[END_REF][START_REF] Kay | A new small platyrrhine and the phyletic position of Callitrichinae[END_REF][START_REF] Meldrum | Nuciruptor rubricae, a new pitheciin seed predator from the Miocene of Colombia[END_REF][START_REF] Takai | A new platyrrhine from the middle Miocene of La Venta, Colombia, and the phyletic position of Callicebinae[END_REF] for recent summaries, see [START_REF] Rosenberger | New World Monkeys[END_REF][START_REF] Kay | Biogeography in deep time -What do phylogenetics, geology, and paleoclimate tell us about early platyrrhine evolution?[END_REF]. Apart from this exceptional past diversity, fossil primates from low latitudes of South America are rare and limited, notably in Amazonia s.l.1 [START_REF] Kay | Large fossil platyrrhines from the Río Acre local fauna, late Miocene, western Amazonia[END_REF][START_REF] Kay | New platyrrhine monkeys from the Solimões Formation (late Miocene, Acre State, Brazil)[END_REF][START_REF] Marivaux | A platyrrhine talus from the early Miocene of Peru (Amazonian Madre de Dios Sub-Andean Zone)[END_REF]Marivaux et al., , 2016a, b;, b;[START_REF] Bond | Eocene primates of South America and the African origins of New World monkeys[END_REF][START_REF] Kay | Parvimico materdei gen. et sp. nov.: a new platyrrhine from the Early Miocene of the Amazon Basin, Peru[END_REF], although this vast land shelters today the most diversified platyrrhine communities of the Americas (e.g., [START_REF] Garber | South American Primates[END_REF]. Because archetypical traits of a modern tropical rainforest seem to have been present in this region of South America for most parts of the Cenozoic [START_REF] Jaramillo | The origin of the modern Amazon rainforest: implications of the palynological and palaeobotanical record[END_REF][START_REF] Jaramillo | Miocene flooding events of western Amazonia[END_REF], an equally large fossil primate diversity is expected to have existed there. However, due to extensive recent alluvial deposition, dense vegetation cover and harsh field conditions, scientists have long been reluctant to explore Amazonia s.l. from a paleobiological perspective. Recent field efforts in Peruvian Amazonia have proven that the Andean foothills had great paleontological potential for highlighting the evolutionary history of New World monkeys. Although very fragmentary, the paleontological evidence recently gathered in this area of Western Amazonia has shed new light on the origin, emergence, and subsequent evolution of platyrrhines [START_REF] Marivaux | A platyrrhine talus from the early Miocene of Peru (Amazonian Madre de Dios Sub-Andean Zone)[END_REF](Marivaux et al., , 2016a, b;, b;[START_REF] Bond | Eocene primates of South America and the African origins of New World monkeys[END_REF][START_REF] Kay | Parvimico materdei gen. et sp. nov.: a new platyrrhine from the Early Miocene of the Amazon Basin, Peru[END_REF][START_REF] Seiffert | A parapithecid stem anthropoid of African origin in the Paleogene of South America[END_REF].

A new primate-bearing locality from Peruvian Amazonia

In the framework of an ongoing paleontological program in the Cenozoic of Peruvian Amazonia, following our works in the Atalaya region (Madre de Dios Department; e.g., [START_REF] Marivaux | A platyrrhine talus from the early Miocene of Peru (Amazonian Madre de Dios Sub-Andean Zone)[END_REF][START_REF] Antoine | Middle Miocene vertebrates from the Amazonian Madre de Dios Subandean Zone, Peru[END_REF], the Fitzcarrald arch area (Ucayali Department, e.g., [START_REF] Antoine | The Middle Miocene (Laventan) Fitzcarrald fauna, Amazonian Peru[END_REF][START_REF] Tejada-Lara | Life in proto-Amazonia: middle Miocene mammals from the Fitzcarrald arch (Peruvian Amazonia)[END_REF] and in Contamana (Loreto Department; e.g., [START_REF] Antoine | A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru[END_REF][START_REF] Antoine | Western Amazonia as a hotspot of mammalian biodiversity throughout the Cenozoic[END_REF], we have recently enlarged our survey area and started new paleontological investigations in the San Martín Department of Peru (Fig. 1A). In this region, close to the western Amazonian/Sub-Andean transition, southeast of the Tarapoto city (TAR), a recent road cut of several kilometers (Shapaja road; Fig. 1B) offers a unique access to a wellexposed Cenozoic stratigraphic section documenting the Eocene-Miocene interval (e.g., [START_REF] Hermoza | The Huallaga foreland basin evolution: thrust propagation in a deltaic environment, northern Peruvian Andes[END_REF][START_REF] Roddaz | Cenozoic sedimentary evolution of the Amazonian foreland basin system[END_REF][START_REF] Klaus | Palaeogene and Neogene brachyurans of the Amazon Basin: a revised first appearance date for primary freshwater crabs (Brachyura, Trichodactylidae)[END_REF][START_REF] Boivin | Early Oligocene caviomorph rodents from Shapaja, Peruvian Amazonia[END_REF]. Miocene fluvial deposits are accessible in the Juan Guerra area, notably along the Río Mayo (Fig. 1B).

These outcrops have been assigned to the lower member of the Ipururo Formation [START_REF] Sánchez Fernández | Geología de los cuadrángulos de Tarapoto, Papa Playa, Utcurarca y Yanayacu 13-k, 13-l, 14-k, 14-l[END_REF][START_REF] Hermoza | The Huallaga foreland basin evolution: thrust propagation in a deltaic environment, northern Peruvian Andes[END_REF]. Our survey of these deposits has resulted in the discovery of a 10-15 cm thick fossil-bearing microconglomerate Figs. 1B and 2A).

The sediment of this layer has yielded a diverse assemblage of aquatic and terrestrial vertebrates, including fishes, anurans, turtles, crocodiles, a small passerine bird, and mammals such as marsupials, hoofed mammals, xenarthrans, a sirenian, bats, rodents, and a primate. In this paper, we describe the few recovered primate dental specimens. Although meager, the primate material documents a small-bodied cebine cebid assigned to Neosaimiri. This monotypic genus is well documented in late Middle Miocene deposits of La Venta, Colombia (Laventan South American Land Mammal Age [SALMA]; Fig. 1A), by the species Neosaimiri fieldsi [START_REF] Stirton | Ceboid monkeys from the Miocene of Colombia[END_REF] (see also [START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF]. Here we describe and compare these new dental remains from Peruvian Amazonia, and discuss the paleobiogeographic implications of that discovery.

Stratigraphic and biochronological context

The 10-15 cm-thick lens which yielded the TAR-31 assemblage consists of a yellowish microconglomerate interbedded within a gray cross-stratified and sandstone-dominated fluvial unit (Fig. 2A). The latter is intercalated between thick violet-gray variegated paleosols pointing to the existence of a meandering river with sustainable floodplain. This unit can be assigned unambiguously to the lower member of the Ipururo Formation, Middle Miocene in age in the Huallaga basin [START_REF] Hermoza | The Huallaga foreland basin evolution: thrust propagation in a deltaic environment, northern Peruvian Andes[END_REF][START_REF] Feussom Tcheumeleu | Depositional environments and landscapes of the upper Miocene Ipururo Formation at Shumanza, Subandean Zone, northern Peru[END_REF]. Among the mammal remains (Fig. 2B), we have preliminarily identified an argyrolagid marsupial, the didelphid marsupial Marmosa (Micoureus) sp., the interatheriine notoungulate Miocochilius sp., the didolodontid Megadolodus sp., as well as a cohort of rodents including among others the adelphomyine octodontoid Ricardomys longidens sensu Walton, 1997, an erethizontoid (cf. Microsteiromys sp.), and the chinchilloids Microscleromys sp. and "Scleromys" sp. (sensu [START_REF] Walton | Rodents[END_REF]. This assemblage strongly recalls that of the lower part of the Villavieja Formation, including the Monkey Beds, in the La Venta area in Ma; e.g., [START_REF] Kay | A new small platyrrhine and the phyletic position of Callitrichinae[END_REF]; geomagnetic ages as revised in [START_REF] Hilgen | The Neogene Period[END_REF] and, to a lesser extent, that of the Quebrada Honda locality in Bolivia (12.5-12.2 Ma; e.g., [START_REF] Croft | The middle Miocene (Laventan) Quebrada Honda fauna, southern Bolivia and a description of its notoungulates[END_REF][START_REF] Brandoni | New remains of Megathericulus patagonicus Ameghino, 1904 (Xenarthra, Tardigrada) from the Serravallian (Middle Miocene) of Bolivia; chronological and biogeographical implications[END_REF] and the Fitzcarrald local fauna in SE Peru [START_REF] Tejada-Lara | Life in proto-Amazonia: middle Miocene mammals from the Fitzcarrald arch (Peruvian Amazonia)[END_REF]. All these localities are Laventan in age (Serravallian; [START_REF] Hilgen | The Neogene Period[END_REF]. Accordingly, the new TAR-31 locality most likely documents the late Middle Miocene Laventan SALMA, a time window with no platyrrhine record in Amazonian lowlands thus far [START_REF] Tejada-Lara | Life in proto-Amazonia: middle Miocene mammals from the Fitzcarrald arch (Peruvian Amazonia)[END_REF][START_REF] Antoine | A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru[END_REF][START_REF] Antoine | Western Amazonia as a hotspot of mammalian biodiversity throughout the Cenozoic[END_REF].

Materials and methods

Fossil recovery and extraction The TAR-31 fossil-bearing locality is a 10-15 cm thick lens of microconglomerate. We excavated and collected ~550 kg of sediments of this lens. When fully dry, the gross sediments were treated by wet screening (two meshes of sieves; 2 mm and 1 mm) directly in the water of the Río Mayo. The coarse residues of screening (≥ 2 mm) were carefully scrutinized by naked eyes in situ (on the riverbank), in order to collect the medium-sized fossil elements. The fine residues (1 mm ≤ fossils < 2 mm) were generally screen/washed twice, dried, and observed under stereomicroscopes in our laboratory camp.

The fossil material consists primarily of bone fragments and tens of isolated teeth, among which the few specimens of primates reported here.

Fossil repository The fossil specimens are permanently housed in the collections of the Vertebrate Paleontology Department of the Museo de Historia Natural -Universidad Nacional Mayor San Marcos in Lima, Peru.

Dental loci, nomenclature and measurements The terminology for primate dentition follows [START_REF] Marivaux | The eosimiid and amphipithecid primates (Anthropoidea) from the Oligocene of the Bugti Hills (Balochistan, Pakistan): new insight into early higher primate evolution in South Asia[END_REF] and the literature cited therein. Teeth were measured (maximum mesiodistal length and maximum buccolingual width) with a microscope fitted with a calibrated reticle (Measuroscope Nikon 10).

High-resolution µCT scan We used X-ray microtomography (μCT scan) for obtaining threedimentional digital models (3D rendering) of the fossils (Figs. 345). Each specimen was scanned with a resolution of 6 µm using a μCT-scanning station EasyTom 150 / Rx Solutions (Montpellier RIO Imaging, ISE-M, Montpellier, France). The crown and roots of each tooth have been virtually delimited by manual segmentation under AVIZO 7.1 software (Visualization Sciences Group). The teeth were prepared within a 'Label Field' module of of the teeth of N. cf. fieldsi described in this paper are available on "MorphoMuseum" [START_REF] Marivaux | 3D models related to the publication: New record of Neosaimiri (Cebidae, Platyrrhini) from the late Middle Miocene of Peruvian Amazonia[END_REF], an online open access platform that aims at enhancing accessibility to 3D models (http://morphomuseum.com).

Optical photography The pictures of Neosaimiri fieldsi teeth from La Venta (Fig. 5) are photographs of casts (originals published by [START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF], whitened using magnesium smoke.

These views are the result of the fusion of multifocus images obtained with an optical stereomicroscope (Leica M 205C) connected to a camera (Leica DFC 420C).

Abbreviations IGM-KU = IGEOMINAS-Kyoto University; MUSM = Museo de Historia Natural -Universidad Nacional Mayor San Marcos; SALMA, South American Land Mammal Ages; † = extinct taxa. Stirton, 1951; Chilecebus † 3 Flynn et al., 1995; Acrecebus † Kay and Cozzuol, 2006; Panamacebus † Bloch et al., 2016. Neosaimiri Stirton, 1951 Neosaimiri cf. fieldsi Studied material MUSM-3888, right M3 (Fig. 3A-H Locality Tarapoto/Juan Guerra locus n°31 (TAR-31), Río Mayo, Shapaja road, San Martín Department, Western Amazonia, Peru (Fig. 1).

Systematic paleontology

Formation and age Ipururo Formation, lower member (Sánchez Hernández et al., 1997;[START_REF] Hermoza | The Huallaga foreland basin evolution: thrust propagation in a deltaic environment, northern Peruvian Andes[END_REF], late Middle Miocene (i.e., Laventan SALMA), based on biochronological data.

Description

Only three of the seven dental specimens found and attributed to this taxon are complete and well preserved. They consist of a M3 (Fig. 3A), a dP2 (Fig. 3I), and a dC 1 (Fig. 4R).

2 Laventiana [START_REF] Rosenberger | Laventiana annectens, new genus and species: fossil evidence for the origins of callitrichine New World monkeys[END_REF], is a genus considered as a junior synonym of Neosaimiri (see [START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF][START_REF] Meldrum | Nuciruptor rubricae, a new pitheciin seed predator from the Miocene of Colombia[END_REF][START_REF] Kay | Biogeography in deep time -What do phylogenetics, geology, and paleoclimate tell us about early platyrrhine evolution?[END_REF]. 3 Chilecebus was originally referred to as Platyrrhini incertae sedis [START_REF] Flynn | An early Miocene anthropoid skull from the Chilean Andes[END_REF]. A recent revision of the fossil material led [START_REF] Kay | Parvimico materdei gen. et sp. nov.: a new platyrrhine from the Early Miocene of the Amazon Basin, Peru[END_REF] to include this taxon in the Cebinae.

Other fossil teeth are broken and the fragments document either halves or quarters of premolars (Fig. 4H,M) and molars (Fig. 4A).

MUSM-3888 (Fig. 3A-H) is identified as a M3, with a crown oval in occlusal outline, longer than wide (Fig. 3A; Table 1), and bearing a single and massive root that results from the complete fusion of a slender mesial root with a large and robust distal root (Fig. 3E-H). Only shallow and vertical grooves, visible on the lingual and buccal aspects of this apparent singleroot, testify to the fusion of the mesial and distal roots. The trigonid is slightly wider and taller than the talonid (Fig. 3A,C,D). The occlusal surface is characterized by four main cuspids (protoconid, metaconid, hypoconid, and entoconid). These cuspids are well defined, somewhat bulbous, and roughly equal in size, except the slightly smaller entoconid (Fig. 3A).

The position of the cuspids describes a square, the two lingual and the two buccal cuspids being aligned mesiodistally, and the two mesial and the two distal cuspids being aligned buccolingually. The trigonid basin is oval, mesiodistally compressed (buccolingual long axis), but particularly broad, approximating half the surface area of the talonid basin (Fig. 3A). The distal margin of the trigonid basin is closed and formed by the sloping mesiolingual and mesiobuccal flanks of the bulbous protoconid and metaconid, respectively, the latter cuspids being linked together by a strong but short, straight (transverse) and moderately-elevated protocristid (Fig. 3A,B,H). The mesial margin of the trigonid basin is formed by an elevated, long and arcuate cristid, which is continuous and uniform, including the premetacristid and the preprotocristid (paracristid). The preprotocristid, strongly attached to the protoconid, extends mesiobuccally (appearing as a long and slightly oblique anterior arm of the protoconid), then it turns abruptly lingually, forming a right angle, and runs lingually to the premetacristid (Fig. 3A-D). The latter cristid is similarly strongly attached to the metaconid, extends mesially (appearing as a long anterior arm of the metaconid), then it turns sharply buccally and runs to the preprotocristid, thereby closing the trigonid basin lingually (Fig. 3A-D). There is no distinct junction between the preprotocristid and the premetacristid (Fig. 3A,B,F). The talonid basin is well delineated, deep, and its bottom is clearly lower than that of the trigonid basin. Its mesial margin appears as a steep-sided wall, formed by the distal flanks of the protoconid and metaconid, and by the straight protocristid linking these two cuspids (Fig. 3A,B,H). Its lingual and buccal margins are elevated and consist of trenchant cristids, which form well-defined walls closing the basin lingually and buccally. The lingual cristid is made by a strong and long pre-entocristid and by a postmetacristid sloping gently backwardly from the apex of the metaconid (Fig. 3A,C,D,G). These two lingual cristids are merged but their junction is undistinguishable. The buccal wall of the talonid basin is made by a trenchant and almost mesiodistally oriented cristid obliqua (marginally positioned). The latter runs from the hypoconid to reach the trigonid wall at a point distal to the protoconid tip (Fig. 3A, C-E).

With such a cristid obliqua configuration, the hypoflexid is virtually inexistent. Distally, the hypocristid is strong, arcuate and links the hypoconid to the entoconid. With wear, the hypoconid and hypocristid form together a claw-like structure, the tip of which (i.e., lingual extremity of the hypocristid) is connected to the entoconid. Due to their bulbous condition, the buccal aspect of the entoconid and the lingual aspect of the hypoconid protrude within the talonid basin, thereby limiting the distal surface of the basin, as if the latter was pinched buccolingually.

MUSM-3890 is a left dP2 (Fig. 3I-M), identified as such thanks to a comparison with homologous dental loci available for N. fieldsi (described and illustrated in [START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF]. This tooth appears single-rooted but a shallow groove visible on the lingual aspect of this buccolingually compressed root (suboval in cross section, with a mesiodistal long axis; Table 1), suggests the presence of both a mesial and a distal roots, strongly merged. The occlusal crown outline of this tooth is triangular, being dominated by a tall and pyramidal protoconid.

In lingual (Fig. 3K) and buccal (Fig. 3M) views, the protoconid apex looks like the sharp tip of a dagger, due to the presence of sloping and trenchant paracristid and protocristid. In occlusal view (Fig. 3I), these two cristids form a nearly flat angle. From the protoconid, the paracristid runs mesially to reach the mesial margin of the tooth. There is no well-defined paraconid in its mesial extremity. In occlusal view, the protocristid is short and slightly arcuate, running distally to reach a minute but conspicuous metaconid, well-separated from the protoconid. This small metaconid is well inferior to the protoconid tip and situated only slightly more lingually to it. There is no talonid development, and the distal sloping flank of the metaconid thus forms the distal margin of the crown. The tooth bears a crowning cingulid at cervix, which is particularly well marked lingually (Fig. 3K), whereas it is more discreet buccally (Fig. 3J, L, M). In mesial (Fig. 3J) and distal (Fig. 3L) views, the buccal cingulid extends inferiorly beyond the inferior margin of the lingual side of the tooth, thereby describing an exodaenodont pattern.

Among upper teeth, only MUSM-3895 is complete (Fig. 4R-V). This simple single-rooted and single-cusped tooth is identified as a right dC 1 . The crown is dominated by a strong and pyramidal cusp, being buccolingually compressed (its base is longer that it is wide; Table 1). Its buccal aspect is steep-sided and marginally positioned, nearly aligned with the vertical buccal margin of the root (Fig. 4S,U). In contrast, its lingual aspect is sloping gently. At the base of the crown, there is no well-marked development of buccal and lingual cingula, but the tooth seems to be eroded, which could have strongly attenuated or erased these traits. There are only small islets of a cingulum observable at the base of the mesiolingual margin of the crown.

Lingually, there is a small enamel swelling situated directly lingual to the main cusp apex. It is not well defined but could point to the presence of a tiny mesiostyle. The latter is linked to the main cusp by a smooth crest, somewhat hardly noticeable, running on the lingual slope of the cusp. The mesial and distal slopes of the main cusp are made by well-marked pre-and postcristae. The precrista is rounded and not well defined, and ends on the mesial crown margin, without noticeable style development. The postcrista, better defined and sharp, ends its course in the distal margin of the crown, where a tiny enamel swelling could correspond to a minute distostyle.

Other dental remains are documented by fragments of upper teeth. MUSM-3893 corresponds to the buccal part of a right P 3 or P 4 (Fig. 4H-L), whereas MUSM-3894 is the lingual part of a left P 3 or P 4 (Fig. 4M-Q). Despite the fragmentary nature of these specimens, their association documents the morphology of a P 3 or P 4 . The latter, when complete, was likely triangular to suboval in occlusal crown outline, with a buccal margin longer than the lingual one (Table 1). The buccal part is dominated by a tall paracone displaying trenchant pre-and postparacristae, mesiodistally aligned, and sloping gently mesially and distally, respectively (Fig. 4J,L). The postparacrista is barely longer than the preparacrista, and connects to a minute but well-defined metacone distally (Fig. 4H-J). The mesial extremity of the preparacrista is faintly damaged, and does not allow the presence or absence of a parastyle to be assessed (Fig. 4H,J,K). The buccal aspect of the paracone is nearly steep sided (Fig. 4I), and bears at it base a discreet and mesiodistally limited buccal cingulum (Fig. 4H,L), which gradually fades distally before to reach the metacone (Fig. 4H,L), whereas it disappears rapidly mesially (Fig. 4K,L). The lingual aspect of the paracone is gently sloping. The distal cingulum and the preprotocrista are well marked (at least their preserved part), and buccally connected at the base of the metacone and the mesial extremity of the preparacrista, respectively. The preserved lingual part (MUSM-3894) is circular, displays a cuspate protocone (but well-inferior to the paracone) and a strong lingual cingulum (Fig. 4M). The protocone is mesially canted, and the cingulum ends directly mesiolingual to the protocone.

There is no mesial cingulum. The protocone displays a well-defined but low postprotocrista, which is curved and distolingually oriented, ending on the lingual cingulum, at the place where a hypocone would normally occur.

Only two small dental fragments document parts of a right upper molar (Fig. 4A): MUSM-3891, a mesiolingual part (Fig. 4B-E), and MUSM-3892, a distobuccal part (Fig. 4F,G). The lingual fragment includes a well-defined and acute protocone, and a strong mesiolingual cingulum, likely bearing a small pericone. The distobuccal fragment documents a metacone region. This buccal cusp displays well-developed and mesiodistally aligned pre-and postmetacristae, the latter being short and connected to a minute metastyle. There is no development of hypometacrista on the lingual aspect of the metacone. The distal aspect of the metacone bear a small spur (enamel accessory ridge), which could correspond to a distal extension of a mesostyle. Given the size of the fragment preserved, we cannot evaluate if a buccal cingulum is present.

Comparisons

The dental material of primates assembled in TAR-31 is quite limited, but the isolated and partial teeth display morphological attributes and proportions (Table 1) that match those characterizing teeth of the cebine cebid Neosaimiri, so far known only by N. fieldsi (Table 2) from La Venta, Colombia (late Middle Miocene; [START_REF] Stirton | Ceboid monkeys from the Miocene of Colombia[END_REF][START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF]. This is particularly shown in the configuration of the trigonid of the lower molar available (M3, MUSM-3888; Figs.

3A-H and 5A), which is mesiodistally compressed but particularly broad, approximating half the surface area of the talonid basin, and also markedly taller than the latter. As on M3 of N.

fieldsi (e.g., IGM-KU 89090; Fig. 5B), the trigonid of the MUSM-3888 M3 (Fig. 5A) is lingually closed by the presence of a strong, elevated and mesially elongated premetacrista. The latter generates, in association with the also long, elevated and mesiobuccally-oriented preprotocristid, an unusual broad trigonid basin, characteristic of cebids (notably cebines), especially well marked on lower molars of Neosaimiri (see Takai, 1994: Figs. 4-6). As on the M3 of N. fieldsi (e.g., IGM-KU 89090; Fig. 5B) and M3 of cebids in general (cebines and aotines), MUSM-3888 has no buccal cingulid, but a cristid obliqua that is long, trenchant, mesially oriented and marginally sided, a configuration which makes the hypoflexid inexistent.

MUSM-3888 differs from documented M3 of N. fieldsi, notably in having its main cuspids appearing slightly more bulbous (but this can be moderated due to wear on MUSM-3888; Figs. 3A-D and5A), the entoconid occupying a more distal position and being lingually opposed to the hypoconid rather than being mesially displaced with respect to the hypoconid, as it does in N. fieldsi (e.g., IGM-KU 89090; Fig. 5B). In addition, the protoconid and metaconid on MUSM-3888 appear buccolingually closer than on M3 of N. fieldsi (Fig. 5B), and the protocristid seems shorter in the former as a result. Regarding the dP2, in addition to a small difference in size (Tables 1 and2), some distinctive morphological details can also be noted between MUSM-3890 (Figs. 3I-M and5C, E) and the known dP2 of N. fieldsi (see [START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF]. The structural complexity of this dental locus is limited, but one of the main noticeable differences relies in the structure of the distal part of the tooth, in particular the development of a tiny hypoconid and a stronger cristid obliqua on known dP2 of N. fieldsi (e.g., IGM-KU 89125; Fig. 5D), dental traits which are only faintly marked on MUSM-3890 (Fig. 5C). The lingual cingulid on MUSM-3890 may also appear somewhat better developed, notably distolingually (Fig. 5E) than on dP2 of N. fieldsi (Fig. 5F), but this dental trait may also vary within the species. Distinctions on the upper premolars are also tenuous. The composite P 3 or P 4 (MUSM-3893 and 3894; Fig. 5G,H) is slenderer than its counterparts in N. fieldsi (e.g., IGM-KU 90009; Fig. 5I), in having buccal and lingual aspects of the paracone and protocone, respectively, much steep sided and less sloping (i.e., less inflated), and in showing a triangular occlusal outline (V-shaped mesial and distal margins) rather than oval (parallel mesial and distal margins). On upper premolars referred to as N. fieldsi (see [START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF], the crests and cingula (lingual and distal) are also better marked than on MUSM-3893 and 3894. The hypocone, although tiny in upper premolars of N. fieldsi (notably on P 4 ; e.g., IGM-KU 90009; Fig. 5I), is still less pronounced in MUSM-3894 (Fig. 5H), appearing as a very discreet small enamel swelling situated at the union of the distal extremity of the postprotocrista with the lingual cingulum. Finally, the upper deciduous canine from TAR-31 (MUSM-3895, a right dC 1 ; Figs. 4R-V and 5J), although slightly smaller (Tables 1 and2), is morphologically roughly similar to its homologous in N. fieldsi (e.g., IGM-KU 89136; Fig. 5K), except for its oval occlusal outline (Fig. 5J) that differs from the rounded outline of this tooth in N. fieldsi (i.e., more inflated). On MUSM-3895 (Figs. 3R-T and 5J), the lingual cingulum is also less developed than on known dC 1 of N. fieldsi (Fig. 5K). The primate dental specimens collected in TAR-31 are strongly reminiscent morphologically to the teeth of N. fieldsi from La Venta, Colombia [START_REF] Stirton | Ceboid monkeys from the Miocene of Colombia[END_REF][START_REF] Takai | New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys[END_REF]. However, given that several aspects of the dental variability from TAR-31 are unknown, we prefer to provide an assignment with open nomenclature (i.e., Neosaimiri cf. fieldsi), instead of formally referring these remains to N. fieldsi, pending the discovery of additional specimens.

Discussion and conclusions

Neosaimiri fieldsi is one of the first primates that was discovered and described from La Venta, Colombia [START_REF] Stirton | Ceboid monkeys from the Miocene of Colombia[END_REF]; Fig. 1A). In the original description, [START_REF] Stirton | Ceboid monkeys from the Miocene of Colombia[END_REF] noted the close relationships between Neosaimiri and the living squirrel monkey, Saimiri, a member of the Cebinae. In being recognized as a distant relative of the modern cebines, Neosaimiri thus emphasized the presence of crown platyrrhines as early as the age documenting the La Venta fauna of the Honda Group (i.e., late Middle Miocene, Laventan SALMA; [START_REF] Madden | The Laventan stage and age[END_REF].

In the same publication, [START_REF] Stirton | Ceboid monkeys from the Miocene of Colombia[END_REF] also completed the description of Cebupithecia Stirton and Savage, 1950, another primate from La Venta widely recognized as a representative of the Pitheciinae, a main subfamily of crown platyrrhines (Pitheciidae; e.g., [START_REF] Fleagle | Fossil New World monkeys[END_REF][START_REF] Kay | Biogeography in deep time -What do phylogenetics, geology, and paleoclimate tell us about early platyrrhine evolution?[END_REF]. Since then, continuing field efforts in the La Venta region (along the Upper Magdalena Valley) have yielded a wide array of stem representatives of modern (crown) Platyrrhini families and subfamilies, including members of atelids, other pitheciids (pitheciines and callicebines), and cebids (notably several callitrichines; see Rosenberger and[START_REF] Rosenberger | New World Monkeys[END_REF][START_REF] Kay | Biogeography in deep time -What do phylogenetics, geology, and paleoclimate tell us about early platyrrhine evolution?[END_REF] for recent summaries and references therein). Over the last decades, the numerous fossil-bearing localities of the Honda Group of La Venta have thus documented a remarkable past diversity of modern Platyrrhini at low latitudes in the Neotropics. Such an exceptional record, however, is unique, and represents only a snapshot of the evolutionary history of New World monkeys. Although the primate fossil record has continued to improve (slowly but considerably) in South America (e.g., [START_REF] Fleagle | New primate fossils from late Oligocene (Colhuehuapian) localities of Chubut Province, Argentina[END_REF][START_REF] Fleagle | New fossil platyrrhines from Santa Cruz Province, Argentina[END_REF][START_REF] Fleagle | New fossil platyrrhines from the Pinturas Formation, Southern Argentina[END_REF][START_REF] Flynn | An early Miocene anthropoid skull from the Chilean Andes[END_REF][START_REF] Kay | A new pitheciin primate from the middle Miocene of Argentina[END_REF][START_REF] Kay | The anatomy of Dolichocebus gaimanensis, a stem platyrrhine monkey from Argentina[END_REF][START_REF] Kay | Parvimico materdei gen. et sp. nov.: a new platyrrhine from the Early Miocene of the Amazon Basin, Peru[END_REF][START_REF] Takai | New fossil materials of the earliest New World Monkey, Branisella boliviana, and the problem of platyrrhine origins[END_REF][START_REF] Tejedor | New fossil platyrrhine from Argentina[END_REF][START_REF] Tejedor | New primate genus from the Miocene of Argentina[END_REF][START_REF] Kay | New platyrrhine monkeys from the Solimões Formation (late Miocene, Acre State, Brazil)[END_REF][START_REF] Kay | A new primate from the early Miocene of Gran Barranca, Chubut Province, Argentina: paleoecological implications[END_REF][START_REF] Kramarz | New Miocene primate fossils from northern Patagonia, Argentina[END_REF][START_REF] Marivaux | A platyrrhine talus from the early Miocene of Peru (Amazonian Madre de Dios Sub-Andean Zone)[END_REF]Marivaux et al., , 2016a, b;, b;[START_REF] Perry | Oldest known cranium of a juvenile New World monkey (Early Miocene, Patagonia, Argentina): Implications for the taxonomy and the molar eruption pattern of early platyrrhines[END_REF][START_REF] Bond | Eocene primates of South America and the African origins of New World monkeys[END_REF][START_REF] Novo | New specimens of platyrrhine primates from Patagonia (Pinturas Formation, Early Miocene)[END_REF][START_REF] Antoine | A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru[END_REF][START_REF] Bloch | First North American fossil monkey and early Miocene tropical biotic interchange[END_REF][START_REF] Novo | Previously unknown fossil platyrrhines (Primates) of Patagonia from the Tournouër collection at the Muséum national d'Histoire naturelle[END_REF][START_REF] Seiffert | A parapithecid stem anthropoid of African origin in the Paleogene of South America[END_REF], virtually none of the species and genera recorded at La Venta had so far been found elsewhere. Only one lower molar recovered in much more recent levels (Huayquerian SALMA) in Acre, Brazil, was tentatively assigned to the alouattine Stirtonia known in La Venta [START_REF] Kay | Large fossil platyrrhines from the Río Acre local fauna, late Miocene, western Amazonia[END_REF]. This reflects the substantial incompleteness of the primate fossil record in South and Central America, rather than a provincialism effect, and shows how severely undersampled paleontologically the tropics are, especially Amazonia s.l., which harbors today's most diversified platyrrhine communities (e.g., [START_REF] Garber | South American Primates[END_REF]. The discovery of Neosaimiri in Peruvian Amazonia (TAR-31), in deposits coeval to those of La Venta (based on biochronological evidence), represents therefore a second record of that genus ca. 1100 km south of La Venta, thereby demonstrating a wider distribution of this taxon at that time (late Middle Miocene). The same is true for the caviomorph rodent cohort, since many of the La Venta genera [START_REF] Walton | Rodents of the La Venta fauna, Miocene, Colombia: Biostratigraphy and paleoenvironmental implications[END_REF][START_REF] Walton | Rodents[END_REF] are also found in TAR-31 (Ricardomys, Microsteiromys, Microscleromys, and "Scleromys"; see Section 1.2; work in preparation). Tectonic and geomorphological studies indicate that the eastern Cordillera of Northern Andes, which separates today the Amazon from the Orinoco basin (and their respective tributaries Río Huallaga in Peru and Magdalena River in Colombia), had not yet uplifted sufficiently to produce a barrier to land vertebrate dispersals (e.g., [START_REF] Lundberg | Miocene characid fishes from Colombia: evolutionary stasis and extirpation[END_REF][START_REF] Hoorn | Andean tectonics as a cause for changing drainage patterns in Miocene northern South America[END_REF][START_REF] Kay | Biogeography in deep time -What do phylogenetics, geology, and paleoclimate tell us about early platyrrhine evolution?[END_REF][START_REF] Anderson | Andean topographic growth and basement uplift in southern Colombia: Implications for the evolution of the Magdalena, Orinoco, and Amazon river systems[END_REF][START_REF] Jaramillo | Miocene flooding events of western Amazonia[END_REF]. The strong faunal similarities between the Fitzcarrald local fauna, TAR-31 and La Venta thus corroborate such a geological observation. The wide distribution of Neosaimiri and associated taxa also suggests that the Pebas Mega-Wetland System (PMWS; e.g., [START_REF] Hoorn | Amazonia through time: Andean uplift, climate change, landscape evolution, and biodiversity[END_REF], located at low latitudes of western South America during the late Middle Miocene (Fig. 6), was not a limiting factor for mammalian dispersals, notably due to the so-called Western Corridor, close to the Andes [START_REF] Croft | The middle Miocene (Laventan) Quebrada Honda fauna, southern Bolivia and a description of its notoungulates[END_REF][START_REF] Tejada-Lara | Life in proto-Amazonia: middle Miocene mammals from the Fitzcarrald arch (Peruvian Amazonia)[END_REF]Marivaux et al., 2016b;[START_REF] Antoine | Western Amazonia as a hotspot of mammalian biodiversity throughout the Cenozoic[END_REF]. In contrast, as already advocated, the PMWS was also likely a source of speciation and diversification, via a complex patchwork of submerged/emerged lands varying through time (e.g., [START_REF] Boonstra | Marine connections of Amazonia: evidence from foraminifera and dinoflagellate cysts (early to middle Miocene, Colombia/Peru)[END_REF]Marivaux et al., 2016b;[START_REF] Antoine | Western Amazonia as a hotspot of mammalian biodiversity throughout the Cenozoic[END_REF]Meseguer et al., in press). The absence of monkeys in coeval deposits of Quebrada Honda (ca. 22°S; Fig. 6) appears to be primarily related to paleoenvironmental constraints, as the concerned area was then at a much lower elevation than today (<1000 m vs. 3200 m a.s.l.; [START_REF] Cadena | Giant fossil tortoise and freshwater chelid turtle remains from the middle Miocene, Quebrada Honda, Bolivia: evidence for lower paleoelevations for the southern Altiplano[END_REF] and as such likely to host primates.

In the Tarapoto/Juan Guerra locus n°31 (TAR-31) of Peruvian Amazonia, we have so far recorded only one primate (Neosaimiri cf. fieldsi), while about ten penecontemporaneous taxa are recorded in coeval deposits of Colombia (La Venta), further documenting the three main families of modern platyrrhines. We should expect a comparable diversity of primates in TAR-31, especially since the caviomorph rodent diversity of TAR-31 is similar or even higher than that of La Venta (work in preparation). Such contrast in the primate record between both fossil-bearing areas may be primarily due to the outcrop access: the TAR-31 locality is a single and finite two-meter wide fossil-bearing lens that was sampled for a short period of time (less than one month in 2016 and 2018), whereas La Venta includes numerous spots sampled during decades over a wider region. These new fossils of primates from TAR-31 are, however, of fundamental importance to further our understanding of the Middle Miocene historical paleogeography of platyrrhines in tropical South America. Paleontological field efforts and researches must then be sustained in this region of Amazonia. locality, based on mammalian taxa of interest, as recorded at La Venta, Colombia (black) and at Quebrada Honda, Bolivia (red). Radioisotopic, biostratigraphic and geomagnetic ages from [START_REF] Kay | A new small platyrrhine and the phyletic position of Callitrichinae[END_REF], [START_REF] Hilgen | The Neogene Period[END_REF], [START_REF] Antoine | Middle Miocene vertebrates from the Amazonian Madre de Dios Subandean Zone, Peru[END_REF][START_REF] Brandoni | New remains of Megathericulus patagonicus Ameghino, 1904 (Xenarthra, Tardigrada) from the Serravallian (Middle Miocene) of Bolivia; chronological and biogeographical implications[END_REF].

Preferred age hypothesis (light gray, ~13.1-12.6 Ma) based on the concurrent range. (2013), [START_REF] Boonstra | Marine connections of Amazonia: evidence from foraminifera and dinoflagellate cysts (early to middle Miocene, Colombia/Peru)[END_REF], and [START_REF] Anderson | Andean topographic growth and basement uplift in southern Colombia: Implications for the evolution of the Magdalena, Orinoco, and Amazon river systems[END_REF]. Paleoecological data from Croft (2007), [START_REF] Cadena | Giant fossil tortoise and freshwater chelid turtle remains from the middle Miocene, Quebrada Honda, Bolivia: evidence for lower paleoelevations for the southern Altiplano[END_REF], [START_REF] Tejada-Lara | Life in proto-Amazonia: middle Miocene mammals from the Fitzcarrald arch (Peruvian Amazonia)[END_REF], and [START_REF] Antoine | A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru[END_REF][START_REF] Antoine | Western Amazonia as a hotspot of mammalian biodiversity throughout the Cenozoic[END_REF].

  ); MUSM-3890, left dP2 (Fig.3I-M); MUSM-3891, lingual part of a fragmentary right M 1 or M 2 (Fig.4B-E); MUSM-3892, distobuccal part of a fragmentary right upper molar (metacone region; Fig.4F, G); MUSM-3893, buccal part of a fragmentary right P 3 or P 4 (Fig.4H-L); MUSM-3894, lingual part of a fragmentary left P 3 or P 4 (Fig.4M-Q); MUSM-3895, right dC 1 (Fig.4R-V).

Figure captions Figure 1 .

 captions1 Figure captions

Figure 2 .

 2 Figure 2. Stratigraphic section and biochronological chart of the Tarapoto/Juan Guerra

Figure 3 .

 3 Figure 3. Lower teeth of Neosaimiri cf. fieldsi from the late Middle Miocene (Laventan SALMA)

  Included genera Cebus Erxleben, 1777; SapajusKerr, 1792; Saimiri Voigt, 1831; Neosaimiri † 2

	Class Mammalia Linnaeus, 1758
	Order Primates Linnaeus, 1758
	Suborder Anthropoidea Mivart, 1864
	Infraorder Platyrrhini Geoffroy Saint-Hilaire, 1812
	Family Cebidae Bonaparte, 1831
	Subfamily Cebinae Bonaparte, 1831

Amazonia sensu latissimo (s.l.) includes the Amazonian Basin (the immense watershed of the Amazon River and its tributaries) and the Guiana Shield plus the subregions such as the Planalto, Gurupí and the low eastern part of Andes (see Eva and Hubert,

2005).

The 2018 field expedition (August/September) in the San Martín Department of Peru and post-field analyses (2018)(2019) were carried out thanks to the support from The Leakey Foundation. Fieldwork in that region was also supported by the National Geographic Society, an "Investissements d'Avenir" grant managed by the French Agence Nationale de la Recherche (CEBA, ANR-10-LABX-25-01), and by the CoopIntEER CNRS/CONICET (n° 252540) and the ECOS-Sud/FONCyT (n° A-14U01) international collaboration programs. New record of Neosaimiri (Cebidae,

renders of 3D digital models of the fossil specimens, obtained by X-ray µCT surface reconstruction. Scale bar = 1 mm.


Marco Garbati
email: marco.garbati@lcis.grenoble-inp.fr

Romain Siragusa

Etienne Perret

Christophe Halopé

Low cost low sampling noise UWB Chipless RFID reader

Keywords: Chipless RFID, reader, jitter, sampli ng noise

teaching and research institutions in France or abroad, or from public or private research centers.

I. INTRODUCTION

The RFID (Radio Frequency Identification) is one of the most widespread technology in the world concerning the identification of objects and animals. Compared to RFID technology, bar-code is widely more employed for the identification of items. This is because of its lower cost in terms of the realization of the tags and readers. In fact today the realization cost of a bar-code tag is nothing compared to a classical UHF RFID tag, characterized by the presence of a chip, that is around 5-10c€ [START_REF] Perret | Radio Frequency Identification and Sensors: From RFID to Chipless RFID[END_REF].

Recently a new kind of RFID tag, characterized by the absence of the chip, has been developing. Indeed the chip and the price of the chip's report on the antenna are the most expensive part of a conventional RFID tag. This new kind of tag, called chipless RFID tag, is intended to play an important role in the future for the identification of items [START_REF] Perret | Radio Frequency Identification and Sensors: From RFID to Chipless RFID[END_REF]. The chipless RFID tag works in UWB, which means in a free band between 3.1 and 10.6 GHz. Each tag needs a suitable reader to collect the information from it. A reader for chipless tag, to be compliant with the European (ETSI) and North American (FCC) regulations in terms of UWB power, sends to the reading tag an UWB impulse, in turn the tag reflects the incoming signal shaping it. The reader can decode the ID of the tag analyzing the shape of the backscattered signal [START_REF] Karmakar | Chipless RFID Reader Architecture[END_REF]. Today there is not chipless RFID reader available in commerce, so to allow the diffusion of the chipless RFID technology a cheap reader needs to be developed. A chipless RFID reader based on the equivalent time principle, in order to decrease its realization cost, has been designed. Subsequently, major improvements have been done in order to decrease dramatically its sampling noise. For this, a second reader architecture has been designed. In fact, to acquire the response from the tag the reader converts it in digital. The AD conversion implies a sampling process of the measuring signal. As we will study more accurately in the third section, because of the jitter of some signals inside of the system, this sampling process is affected by noise, which affects especially the component of the measuring signal at higher frequencies (that is to say the fast variations of the signal in time). In addition, the impulse generator used for chipless technology presents lower power at higher frequencies. Thus, reducing the sampling noise of the reader is fundamental to guarantee suitable performance for reading chipless RFID tag. This paper is structured as follow. The first section describes the equivalent time principle and put it in relation with the block diagram of the first version of the chipless RFID reader. The second section describes some results of measure performed with the reader presented in the previous section. The third one introduces the second reader version, designed in order to decrease its sampling noise, and presents the same measures realized with the previous reader.

II. EQUIVALENT TIME PRINCIPLE AND BLOCK DIAGRAM OF THE FIRST DESIGNED READER

The equivalent time approach is based on the stationary character of the measuring signal. In case of chipless RFID tags this signal is the sign of the tag, which is the reflected signal by the tag, after an interrogation from the reader [START_REF] Perret | Radio Frequency Identification and Sensors: From RFID to Chipless RFID[END_REF]. In the equivalent time approach the reader sends a discrete number of UWB impulses to the tag and, for each backscattered signal, it acquires only few points. For each receiving signal the sampling frequency of the reader is very low, compared with the UWB, and the acquisition process is shifted in time of few picoseconds. After the end of the acquisition process the reader rearranges all the acquired samples, in order to reconstruct the backscattered signal from the tag, and so to identify its ID [START_REF] Karmakar | Chipless RFID Reader Architecture[END_REF].

The Fig. 1 shows the block diagram of our reader. It is composed by two different PCBs connected through a VITA 57.1 MC LPC connector. The control unit is entrusted by a FPGA device, the Spartan 6 from Xilinx, in its SP601 evaluation board. The smallest PCB on top represents the RF part and is basically composed by a sample and hold amplifier, an ADC and a delay generator. The reader samples each UWB backscattered signal with a very low frequency, 67 MHz, thanks to the high performance sample and hold amplifier which has an input bandwidth of 10GHz. It is capable to sample an UWB signal and maintain its output constant during an entire clock cycle in order to let the following ADC to digitize it. Obviously the ADC, presenting a constant input for an entire clock cycle, is not affected by sampling noise. For each backscattered signal the reader takes only few points. Thanks to the delay generator the sampling clock is delayed of 10 ps for each receiving signal. It allows the system to obtain an equivalent time sampling rate of 100 GSa/s. The impulse generator is triggered by the low sampling frequency of the reader. Thanks to it we can tune the delay generator in order to acquire few samples for each receiving pulse, at known and controlled positions, except for the presence of any jitter which can disturb the acquisition.

III. MEASUREMENT RESULTS FOR THE FIRST DESIGNED READER

The sampling noise of a chipless RFID reader is correlated with the jitter of some of its signals, which provoke the acquisition of some samples of the input in an incorrect position in time.

Later, in the reconstruction process, it will affect the correctness of the reconstructed signal. To clarify the concept of sampling noise we can take as example an ADC. Assuming the converter performing the sampling, of its analog input, at each clock event, represented by its rising edge, and supposing it affected by jitter. Hence the converter will sample, and therefore convert, a value of tension taken in a wrong and unknown position on time. Then, in the digital world, the incoming signal will be reconstructed assuming a sample period constant and equal to the nominal clock period. Since that at each point in time will be coincided a digital value, of a sample, taken not exactly at that position in time, from the ADC, but at a different one because of the jitter that affects the clock. This means the digital value assigned at that point is wrong. The mistake will be higher as higher is the slew rate of the incoming signal. For a harmonic signal the slew rate is directly proportional to its frequency and amplitude. Thus the problem of sampling noise is more significant as the frequency increases. Supposing a Gaussian jitter, the following equation gives the relation between the jitter and the sampling noise [START_REF] Geng | Evaluation of Fast ADCs for Direct Sampling RF Field detection for the european xfel and ilc, 24th Linear Accelerator Conference[END_REF].

σ = √2 σ .
Where σ is the deviation standard of the jitter and σ is the same but of the error introduced on the acquired signal. The signal to be sampled is a harmonic with amplitude A and frequency f. The reader has a bistatic configuration where, through an UWB transmitting antenna, the UWB impulse is sent to the tag and its response is captured by another UWB antenna. For our measures the two antennas have been disconnected. The output of the reader, represented by the output of the impulse generator, has been directly connected with its input, the input of the LNA amplifier, through the interposition of an attenuator, and some acquisition has been performed. To appreciate the effect of the sampling noise of the acquired response and the equivalent time principle, a comparison between the UWB impulse, measured with a high performance DSO, and the input of the ADC of the reader is reported in Fig.

2.

The duration of the impulse, less than 1 ns, is very low if compared with the clock period, 15ns, of the reader. Therefore, for each impulse sent by the impulse generator, at most one point of it is acquired by the system. This is the reason why, in fig. 2, the shape of the measured input of the ADC of the reader can follow the shape of the impulse acquired with the DSO.

Comparing the two curves is clear that the acquisition made with our reader is affected by sampling noise. This is especially evident in the rising and falling edges of the impulse, where its slew rate is bigger.

IV. LOW JITTER READER DESIGN AND MEASUREMENT RESULTS

There are three signals that establish the position in time of each sampling event, for the sample and hold amplifier, compared with the signal coming from the tag. These three To decrease dramatically the sampling noise, two design choices have been implemented on the second developed reader. The first one was the design of a multi-clock system where the ultra-low jitter clock generator, for the RF board, is placed directly on that board. Moreover it is independent from the clock used for the FPGA that is located on the evaluation board SP601. The second choice was to keep the connection between the trigger signal, for the impulse generator, and the FPGA but getting the rising edge instant of the trigger signal, which commands the impulse generator, independent from the FPGA. It can be obtained with a high performance low jitter AND gate placed on the RF board, where in one input is presented the external clock located on that board, which means a low jitter signal, and in the other one the signal that comes from the FPGA characterized by an high jitter.

The Fig. 3 shows the new reader version. We can recognize the ultra-low jitter clock generator presented on the RF board and the AND gate. In order to ensure a low jitter system, the RF PCB has been carefully designed in order to optimize the signal integrity. Moreover have been chosen components characterized by ultra-low jitter with suitable digital standards. The measure of the period jitter of the sampling clock, of the sample and hold amplifier, for both the readers has been performed. For first version of the reader the jitter presents a standard deviation of 7.34ps and a maximum of 115.7ps meanwhile it is of only 2.45ps in the latest version with a maximum of only 16.31ps over 1.5k cycles measured. In Fig. 4 is reported the same measure of Fig. 2 performed with the second reader. Clearly the second reader presents a much lower sampling noise especially where the slew rate is bigger, which is in the rising and falling edges of the impulse. Indeed the width of the UWB impulse is of only 70 ps. Besides, the already low sampling noise may steel decreased through an averaging of different acquisitions.

CHIPLESS RFID TAG

The low sampling noise of this new reader makes it suitable to be used as chipless RFID reader and it is largely affordable. Indeed, excluding the two antennas, its realization cost is about 2000€ where the most expensive components are the impulse generator (900€) and the sample and hold am plifier (700€).

The two presented reader have approximately the same realization cost but a significant difference in terms of performance.

V. CONCLUSION

In this article has been shown how to design a high performance low cost reader for chipless RFID applications. It has been shown how to decrease the sampling noise, which is vital in a time equivalent approach system for UWB, through the correct design of the reader.

Fig. 1 .

 1 Fig. 1. Block diagram(A) and photo(B) of the first version of the realized reader for chipless RFID applications. The control unit is entrusted on a FPGA Xilinx spartan 6 on the evaluation board SP601. The RF part is the smallest PCB on top of the SP601.

Fig. 2 .

 2 Fig. 2. Comparison between the attenuated output of the pulse generator, measured with a DSO, and the input of the ADC of the first reader in order to appreciate the sampling noise of the system and the equivalent time algorithm.

Fig. 3 .

 3 Fig. 3. Block diagram(A) and photo(B) of the second realized reader for chipless RFID tags. The control unit is entrusted on a FPGA Xilinx spartan 6 on the evaluation board SP601. The RF part is the smallest PCB on top of the SP601. The RF PCB presents a second clock generator and an ultra-low jitter AND gate to decrease the sampling noise of the system.

Fig. 4 .

 4 Fig. 4. Comparison between the attenuated output of the pulse generator, measured with a DSO, and the input of the ADC of the second reader in order to appreciate the sampling noise of the system and the equivalent time algorithm.