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South American Crocodilian diversity at the Lake Pebas System During the Miocene era
Joseph Fossil posted a topic in General Fossil Discussion
Image of a Reconstruction of the Caiman Mourasuchus and Prehistoric Dolphins in Miocene Venezuela by Julio Lacerda Image Source: https://www.facebook.com/art.julio.lacerda/photos/mourasuchus-was-a-very-large-caiman-with-a-distinctly-flat-head-and-numerous-sma/2971939362916938/?_rdr In the Northern and Central Basins of Miocene South America between 23-5.3 Million Years ago, there was a giant system of lakes known as Lake Pebas. Fed by rivers directly connected to South America’s Caribbean Atlantic Coast, this lake system at its largest covered an area slightly bigger than 1,000,000 square kilometers (km2) in what is today part of Brazil, Colombia, Peru, Venezuela, and Bolivia. The lake system was home to a variety of life including a vast diversity of dugongs, fish, dolphins, land mammals, and Crocodilians (when I say crocodilians, I mean the general group within the archosaur family that includes Crocodiles, Gavialoids, and Caimans). Image of Reconstruction of Lake Pebas Image Source: https://www.researchgate.net/figure/Palaeogeographical-model-of-northwestern-South-America-during-the-Middle-Miocene-some-14_fig6_254893768 While Crocodilian diversity decreased globally after the warm Paleocene and Eocene eras, emergence of the lake pebas system paved the way for an explosion in diversity for these semi-aquatic reptiles in Northern South America. This is best demonstrated by the vast and diverse Miocene crocodilian fossils found in the Urumaco Formation and Pebas Formation. https://www.sciencedirect.com/science/article/abs/pii/S0895981118303699 https://igeo.ufrj.br/inc/isc/3/3_87-Souza_Filho_etal_2020_Melanosuchus_latrubessei.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4375856/ These heyday for South American crocodilians saw the emergence of some of the largest aquatic crocodilians currently known on Earth since the Creteaceous and Paleocene eras, including Giant Caimans Purassaurus and Mourasuchus amazonensis. Image of Reconstructions of the sizes compared to an adult Human of several notable Crocodilians from Lake Pebas by Armin Reindl Image Source: https://www.deviantart.com/arminreindl/art/Crocodilians-of-the-Pebas-Megawetlands-900353328 The Lake Pebas system would persist up until the formation of the Andes Mountains during the Late Miocene. This decreased the size of the Pebas lake system and ultimately help give rise to one of the World’s most spectacular river systems, the Amazon. Crocodilian diversity in the region decreased as well and now only a few crocodilian genera inhabit South America currently. Lake Pebas is also the primary reason why the Amazon River system is home to freshwater stingrays, freshwater manatees, and freshwater dolphins. When Lake Pebas started to decrease in size, those creatures successfully adapted to the more freshwater environments of the Amazon River. Here's a list of all the currently known crocodilian genera and species that lived in the Miocene Lake Pebas system. If I forget any examples, please let me know and I'll add the examples to the list promptly. Unnamed Paleosuchus sp. (Alligatoridae) (Miocene, 16.0-11.6 Million Years ago) (grew up to 1.2-1.4 meters (3.9-4.6 feet) in length) Kuttanacaiman (Alligatoridae) (Miocene, 15.97-11.6 Million Years ago) (grew up to 1.71-1.88 meters (5.62-6.20 feet) in length) Gnatusuchus (Alligatoridae) (Miocene, 11.6-5.3 Million Years ago) (grew up to 1.49-1.67 meters (4.89-5.50 feet) in length) Gryposuchus (Gavialidae) (Miocene, 16.3-5.3 Million Years ago) (grew up to 10 meters (33 feet) in length) (five species currently known, four species lived in the adjacent rivers of and in Lake Pebas itself) G. jessei (Miocene, 11.6-7.2 Million years ago) G. pachakamue (Miocene, 11.6-7.2 Million Years ago) G. croizati (Miocene, 11.6-5.3 Million Years ago) G. colombianus (Miocene, 16.3-11.8 Million Years ago) (Note: One unnamed Gryposuchus sp. May have survived up to the Pleistocene, 2.6-0.012 Million Years ago in what is now Paricao, Brazil) http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=38417&max_interval=Quaternary&country=Brazil&is_real_user=1&basic=yes&type=view&match_subgenera=1 Hesperogavialis (Gavialidae) (Miocene, 11.6-7.2 Million Years ago) (grew up to 10 meters (33 feet) in length) Brasilosuchus (Gavialidae) (Miocene, 9 Million Years ago) (grew up to 3.6-3.9 meters (11.9-12.9 feet) in length) Charactosuchus (Crocodylidae) (Eocene-Miocene, 48.6-7.2 Million Years ago) (grew up to 3.6-3.9 meters (11.9-12.9 feet) in length) (three species currently known, two species lived in the adjacent rivers of and in Lake Pebas itself) C. fieldsi (13.8-7.2 Million Years ago) C. sansoai (11.6-7.2 Million Years ago) Mourasuchus (Alligatoridae) (15.9-5.3 Million Years ago) (Largest Mourasuchus sp. Grew up to 4.7-5.9 meters (15.4-19.3 feet) in length) (five species currently known (including one unnamed Mourasuchus sp. From Bolivia), four species lived in the adjacent rivers of and in Lake Pebas itself) M. amazonensis (Miocene, 9.0-6.8 Million Years ago) M. pattersoni (Miocene, 9.0-6.8 Million Years ago) M. atopus (Miocene, 15.9-11.8 Million Years ago) M. arendsi (Miocene, 11.6-5.3 Million Years ago) Unnamed Caiman sp. (Based on Specimen UCMP 39978) (Alligatoridae) (Miocene, 15.97 Million Years ago) (size: NA) Caiman wannlangstoni (Alligatoridae) (Miocene, 13.8-5.3 Million Years ago) (grew up to 1.7-1.9 meters (5.5-6.2 feet) in length) Caiman brevirostris (Alligatoridae) (Miocene, 11.6-7.2 Million Years ago) (grew up to 1.7-1.9 meters (5.5-6.2 feet) in length) Broad-snouted caiman (Caiman latirostris) (Miocene-Present, 9.0-0.0 Million Years ago) (grows up to 2.0-3.5 meters (6.5-11.4 feet) in length) (still extant in the present) Acresuchus (Alligatoridae) (Miocene, 9.0-7.2 Million Years ago) (grew up to 3.4 meters (11.2 feet) in length) Purussaurus (Alligatoridae) (Miocene, 16.3-5.3 Million Years ago) (grew up to 9.2-10.9 meters ( 30.2-35.7 feet) in length) (four species currently known (including one unnamed Purussaurus sp. From Panama), three species lived in the adjacent rivers of and in Lake Pebas itself) P. brasiliensis (Miocene, 9.0-7.2 Million Years ago) P. neivensis (Miocene, 13.8-11.8 Million Years ago) P. mirandai (Miocene, 11.6-5.3 Million Years ago) Melanosuchus latrubessei (Alligatoridae) (Miocene, 10.89 Million Years ago) (grew up to 4 meters (13.1 feet) in length) Globidentosuchus (Alligatoridae) (Miocene, 11.6-6.8 Million Years ago) (grew up to 1.72 meters (5.6 feet) in length) Hope you all find this helpful!!! -
This may be the biggest turtle that ever lived By Laura Geggel, Live Science, February 14, 2020 This jaw-droppingly huge specimen is the largest known complete turtle shell on Earth. https://www.livescience.com/largest-turtle-shell-on-earth.html Extinct South American giant turtle had 10-foot-wide horned shell By Brooks Hays, UPI, February 13, 2020 https://www.upi.com/Science_News/2020/02/13/Extinct-South-American-giant-turtle-had-10-foot-wide-horned-shell/9841581541088/ The paper is: E.-A. Cadena, T. M. Scheyer, J. D. Carrillo-Briceño, R. Sánchez, O. A Aguilera-Socorro, A. Vanegas, M. Pardo, D. M. Hansen, and M. R. Sánchez-Villagra, 2020. The anatomy, paleobiology, and evolutionary relationships of the largest extinct side-necked turtle. Science Advances, Vol. 6, no. 7, eaay4593 DOI: 10.1126/sciadv.aay4593 https://advances.sciencemag.org/content/6/7/eaay4593 Yours, Paul H.