Periodic Reporting for period 1 - DISPERSAL (A climatic or tectonic control on early primate dispersal? A new approach to investigate species dispersal in deep time)
Reporting period: 2022-10-01 to 2025-03-31
Recent studies show that the distribution of many modern terrestrial species can be explained by several episodes of large-scale dispersal and that these episodes will become more numerous under climatic stress. However, their underlying mechanisms remain poorly understood.
Long-distance dispersals across marine barriers, often referred to sweepstakes dispersals, have always been assumed to be an unpredictable process in which taxa overcome a geographic barrier in a random manner. Yet, there are many instances of dispersals across marine barriers that appear coordinated and non-random. New paleontological findings show that during a short time period marked by intense climate variations, 40 to 35 million years ago, Asian anthropoid primates and rodents crossed 500 km of Tethys Sea to reach Africa and 800 km of South Atlantic Ocean to reach South America.
The EU-funded DISPERSAL project investigates the origins and mechanisms of large-scale dispersal by using the ancient dispersal of Asian primates and rodents to South America as a case study. The project proposes a combination of paleoclimatic, paleogeographic, and paleontological approaches to resolve how these mammals dispersed across seaways and continents and identify the external forcing mechanisms that render large-scale dispersal non-random.
Long-distance dispersals across marine barriers, often referred to sweepstakes dispersals, have always been assumed to be an unpredictable process in which taxa overcome a geographic barrier in a random manner. Yet, there are many instances of dispersals across marine barriers that appear coordinated and non-random. New paleontological findings show that during a short time period marked by intense climate variations, 40 to 35 million years ago, Asian anthropoid primates and rodents crossed 500 km of Tethys Sea to reach Africa and 800 km of South Atlantic Ocean to reach South America.
The EU-funded DISPERSAL project investigates the origins and mechanisms of large-scale dispersal by using the ancient dispersal of Asian primates and rodents to South America as a case study. The project proposes a combination of paleoclimatic, paleogeographic, and paleontological approaches to resolve how these mammals dispersed across seaways and continents and identify the external forcing mechanisms that render large-scale dispersal non-random.
The project is divided into four intermediate, inter-related research directions:
(1) refining the timing and biogeographic patterns of the ancient dispersal of primates and other mammals out of Asia. As of Fall 2024, we have focused our paleontological fieldwork and geochronological dating on field sites in Turkey and Kazakhstan, as well as prospected for other sites in central Asia (Tajikistan, Uzbekistan). New paleontological material has been excavated at these sites, and they have been sampled for various geochemical, magnetic and biostratigraphic dating methods.
(2) understanding its paleoclimatic framework. Two PhD students are currently studying the paleoclimatic and paleobotanical record of several fossil localities along the hypothetical itinerary of dispersal in central Asia and the near East, using isotope geochemistry tools and pollen identification. We have set up a complete new lab for clumped isotope measurements, a new isotopic tool that helps reconstructing ancient climatic parameters.
(3) determining the most likely mechanism for overwater crossing and how paleogeography impacted it. One postdoc is currently working on drawing high-resolution paleogeographic maps based on tectonic and paleomagnetic data. A later step starting in late 2025 will consist in modeling with a Global Climate Model the expansion of ecosystems and the oceanic currents that could have favored the dispersal.
(4) integrating this knowledge into a new software for estimating past dispersals, applicable to this and other dispersal events. This software will be later developed, starting in 2026.
(1) refining the timing and biogeographic patterns of the ancient dispersal of primates and other mammals out of Asia. As of Fall 2024, we have focused our paleontological fieldwork and geochronological dating on field sites in Turkey and Kazakhstan, as well as prospected for other sites in central Asia (Tajikistan, Uzbekistan). New paleontological material has been excavated at these sites, and they have been sampled for various geochemical, magnetic and biostratigraphic dating methods.
(2) understanding its paleoclimatic framework. Two PhD students are currently studying the paleoclimatic and paleobotanical record of several fossil localities along the hypothetical itinerary of dispersal in central Asia and the near East, using isotope geochemistry tools and pollen identification. We have set up a complete new lab for clumped isotope measurements, a new isotopic tool that helps reconstructing ancient climatic parameters.
(3) determining the most likely mechanism for overwater crossing and how paleogeography impacted it. One postdoc is currently working on drawing high-resolution paleogeographic maps based on tectonic and paleomagnetic data. A later step starting in late 2025 will consist in modeling with a Global Climate Model the expansion of ecosystems and the oceanic currents that could have favored the dispersal.
(4) integrating this knowledge into a new software for estimating past dispersals, applicable to this and other dispersal events. This software will be later developed, starting in 2026.
So far, our only peer-reviewed results are paleontological findings made in the framework of the project, which help refining the fauna associated with the ancient dispersal of primates and rodents out of Asia. In the short term (in 2025), we expect to publish several studies that clearly detail the paleogeographic, climatic and geochronological context of the dispersal, before starting the modeling and software development work. Once this is achieved, the project will set the founding steps of a holistic method to evaluate the mechanisms of all dispersal events in deep time, allowing new interpretations about the modern, past and future distribution of species; it will additionally solve one of the biggest mysteries in paleontology, as this episode ranks among the most pivotal events during all of primate evolutionary history.