Fullux Posted December 20, 2023 Share Posted December 20, 2023 Howdy all, I've seen a lot of fossils from Alligator americanus, but none from Crocodylus americanus, yet both are present in the modern day. Did C. americanus emerge later than A. americanus or are fossils of C. americanus being labeled as A. americanus for convenience? 1 Link to comment Share on other sites More sharing options...
Al Dente Posted December 20, 2023 Share Posted December 20, 2023 From here- https://repositories.lib.utexas.edu/server/api/core/bitstreams/9da65e24-6dfa-4cd8-bd2d-05231e68196c/content 2 Link to comment Share on other sites More sharing options...
digit Posted December 21, 2023 Share Posted December 21, 2023 53 minutes ago, Fullux said: Howdy all, I've seen a lot of fossils from Alligator americanus, but none from Crocodylus americanus, yet both are present in the modern day. Did C. americanus emerge later than A. americanus or are fossils of C. americanus being labeled as A. americanus for convenience? You're looking in different places that I do--I've never seen fossils of either of these two taxa. I've seen "Alligator americanus" pop up in a few internet searches but I don't believe this is a valid species nor a junior synonym to the extant Alligator mississippiensis. I've never seen any fossils attributed to A. americanus. The binomial "Crocodylus americanus?" Laurenti, 1768 is considered a very old junior synonym to Crocodylus acutus, the American Crocodile. This species dates back around 2.6 Ma to the Pleistocene but I cannot say that I've ever seen a fossil attributed to this taxon. Alligator teeth are fairly common in the fossil record. In Florida the record goes back to Alligator olseni from very early in the Miocene (16-19 and possibly up to 23-22 Ma): https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/species/alligator-olseni/ There are a number of undescribed species from the Florida fossil record spanning the millions of years from A. olseni to our extant A. mississippiensis. The majority of gator teeth recovered by amateur (and professional) paleontologists in Florida likely are attributable to A. mississippiensis or one of the intermediate species that preceded it. Crocodile teeth (more narrowly acute with multiple longitudinal ridges and not just the two large carinae found on gator teeth) can be found in Florida but they are significantly more uncommon than gator teeth--likely a couple orders of magnitude less common. I have hundreds of gator teeth in my collection but probably 1 or 2 croc teeth. Our Miocene crocodile was previously known as Gavialosuchus americanus but it now goes by the new binomial Thecachampsa americana. I believe any Florida fossil crocodiles likely belong to this taxon (and not Crocodylus americanus). https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/species/thecachampsa-americana/ The Thecachampsa fossils are significantly less common than the Alligator fossils. This may be due to the limited time period this species was in Florida (13-6 Ma) or possibly it was restricted to marginal habitats (estuarine and coastal) and didn't have as large of a range as the more ubiquitous alligators. Hope this (somewhat) answers your original question Cheers. -Ken Link to comment Share on other sites More sharing options...
Fullux Posted December 21, 2023 Author Share Posted December 21, 2023 (edited) 38 minutes ago, digit said: You're looking in different places that I do--I've never seen fossils of either of these two taxa. I've seen "Alligator americanus" pop up in a few internet searches but I don't believe this is a valid species nor a junior synonym to the extant Alligator mississippiensis. I've never seen any fossils attributed to A. americanus. The binomial "Crocodylus americanus?" Laurenti, 1768 is considered a very old junior synonym to Crocodylus acutus, the American Crocodile. This species dates back around 2.6 Ma to the Pleistocene but I cannot say that I've ever seen a fossil attributed to this taxon. Alligator teeth are fairly common in the fossil record. In Florida the record goes back to Alligator olseni from very early in the Miocene (16-19 and possibly up to 23-22 Ma): https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/species/alligator-olseni/ There are a number of undescribed species from the Florida fossil record spanning the millions of years from A. olseni to our extant A. mississippiensis. The majority of gator teeth recovered by amateur (and professional) paleontologists in Florida likely are attributable to A. mississippiensis or one of the intermediate species that preceded it. Crocodile teeth (more narrowly acute with multiple longitudinal ridges and not just the two large carinae found on gator teeth) can be found in Florida but they are significantly more uncommon than gator teeth--likely a couple orders of magnitude less common. I have hundreds of gator teeth in my collection but probably 1 or 2 croc teeth. Our Miocene crocodile was previously known as Gavialosuchus americanus but it now goes by the new binomial Thecachampsa americana. I believe any Florida fossil crocodiles likely belong to this taxon (and not Crocodylus americanus). https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/species/thecachampsa-americana/ The Thecachampsa fossils are significantly less common than the Alligator fossils. This may be due to the limited time period this species was in Florida (13-6 Ma) or possibly it was restricted to marginal habitats (estuarine and coastal) and didn't have as large of a range as the more ubiquitous alligators. Hope this (somewhat) answers your original question Cheers. -Ken Alligator mississippiensis* That was a typo on my part. And yes, that does clear some things up, thank you. Edited December 21, 2023 by Fullux 1 Link to comment Share on other sites More sharing options...
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