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Showing results for tags 'maastrictian cretaceous'.
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Questions about Paleocene records of the Bird Asteriornis
Joseph Fossil posted a topic in General Fossil Discussion
I'm researching bird fauna from the Danian Paleocene era recently and I have some questions about a particular bird, Asteriornis maastrichtensis. It was discovered in late 2019 in Maastrictian deposits of the Maastricht Formation, Cretaceous dating 66.8-66.7 Million Years ago in what is now Belgium and was pretty small in size, about the size of a small duck and weighed only 394 grams when alive. https://www.nature.com/articles/s41586-020-2096-0 Asteriornis is the earliest confirmed Neognathae (a group of birds of which the majority of birds alive today belong to) and it's oldest remains date to just around One Million Years before the Cretaceous-Paleocene Astroid impact wiped out that last of the non-avian dinosaurs. I've seen a lot of people say that this bird species survived the Cretaceous-Paleocene Extinction event into the Paleocene. It's small size and diet of seeds make it a good candidate to have survived the event, but I haven't found any definitive records yet of Asteriornis from the early Paleocene. What I'm wondering is did Asteriornis survive the Cretaceous-Paleocene Mass Extinction Event 66 Million Years ago and are there any records of Asteriornis that date definitively to the Paleocene era?- 6 replies
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In a previous post, I discussed if Tyrannosaurus rex (Tyrannosaur, Western North America) (Late Cretaceous 68-66 Million Years ago) was able to colonize Eastern North America as the Western Interior Seaway retreat by the early Maastrichtian (I received excellent feedback from other four members, notably @Troodon, that this was prevented by the KT Mass Extinction event 66 Million Years ago). As a result, I don't believe Tyrannosaurus rex was able to effectively colonize Eastern North America (as far as I'm currently aware). However, looking over some records of Late Cretaceous Tyrannosaur fossils, I do believe that a Tyrannosaurid (Yes a Tyrannosaurid) was able to colonize part of Eastern North America in the area of what is today Chronister well, Bollinger County, Missouri! Not much is known about this Tyrannosaur genera, but here is the info I could find on it! Unnamed Tyrannosauroidea genus (Tyrannosaur) (McNair Sand Member of the Ripley Formation-Missouri, US, North America) (Late Cretaceous, 70-66 Million Years ago) (Size unknown) http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=38606&max_interval=Cretaceous&country=United States&state=Missouri&is_real_user=1&basic=yes&type=view&match_subgenera=1 https://www.lakeneosho.org/Ozarks/Chronister2.html https://www.sos.mo.gov/CMSImages/Publications/symbols/dinosauressay.pdf Photographs of the Chonister well Tyrannosaur specimens have also been tricky to find, the only ones I've found were shown during an August 2016 Science in St. Louis Seminar series lecture by Geologist Dr. Micheal Fix, Ph.D., Associate Teaching Professor, Department of Physics of University of Missouri-St.Louis titled Monster in the Hollow: The Story of Missouri's Ozark Dinosaurs. The presentation also showed a photograph of a decent sized Dromeaosaurid tooth from the same site in Missouri!
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- tyrannosauroidea
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