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To pass some time I've been recently researching early Paleocene life and I keep coming back to researching (in my view) the two strangest and controversial Late Cretaceous-Early Paleocene Formations I know of. These are the Hornerstown Formation dating 66.5-65.5 Million Years ago in what is now New Jersey, U.S. And the Takatika Grit Formation dating 66.5-60.0 Million Years ago in what is now the Chatham Islands, New Zealand. https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=0b3baee9ab1afc7973337f5047495b723fcfa4f2 https://www.researchgate.net/publication/315461615_The_age_of_the_Takatika_Grit_Chatham_Islands_New_Zealand https://www.sciencedirect.com/science/article/abs/pii/S0195667109000184?via%3Dihub I've read many reports about these formations and the pretty controversial stuff that's been found in both these areas (Paleocene ammonites and reports of archaic marine reptiles like Paleocene Mosasaurs). I'm really not 100% sure what to make of this as I've heard conflicting hypotheses on whether these more archaic marine reptile fossils were reworked from older formations while others say it's not too too likely? https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/maastrichtian-ammonites-from-the-hornerstown-formation-in-new-jersey/4F051D07668B7B893EEFECF0506E2F1B https://bioone.org/journals/acta-palaeontologica-polonica/volume-57/issue-4/app.2011.0068/Short-Term-Survival-of-Ammonites-in-New-Jersey-After-the/10.4202/app.2011.0068.full For most of these "controversial" specimens, I would say reworking is likely while some I'll admit I'm not sure? For the Mosasaurs, it's clear that the astroid impact 66 Million Years ago caused their total extinction, but I'm still not 100% convinced that none emerged from the event alive (at least barely) and swam the seas in the very first days of the Danian Paleocene but not too long after. Unlike the mostly terrestrial Non-Avian Dinosaurs, which could only hide in so many places and it's very unlike more than a tiny amount of individuals (not enough to support a population) made it into the Paleocene, the Oceans have slightly more areas to hide and more even for endothermic air breathing animals like Mosasaurs (though as an endotherm, food does become a major issue especially when the ocean food chain nearly collapsed completely). What I'm wondering is how valid are at least "some" of these supposed archaic marine reptile and ammonite fossils from the earliest Paleocene sections of the Hornerstown Formation and the Takatika Grit? Also, of all the Maastrichtian Mosasaurs known so far, which ones would have been the mostly likely to have (at least briefly) survived the Cretaceous-Paleocene Extinction Event of 66 Million Years ago (would it have been generalist feeders, ones that specialized in deep sea hunting, ones with cosmopolitan distributions, ones small by mosasaur standards but still around the same size of the few confirmed large reptiles that survived the event like the 8 meter (26 feet) in length Thoracosaurus, or ones with all these traits and advantages)?

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?

Around 66 Million years ago, at the end of the Maastrichtian stage of the Late Cretaceous period, an astroid struck what is now the Yucatan Peninsula of Mexico. The subsequent impact and its effects caused the KT mass extinction event. The event wiped out 75% of all life on Earth. This included all the non-avian dinosaurs and most genera of marine reptiles. The end of the event also heralded the beginning of the Cenozoic era with the Paleocene period (66.0-56.0 Million years ago), and the dawn of the age of the mammals (one of the survivors from the Cretaceous Paleocene extinction event). But what most people don't realize is that in large areas of the planet, mammals didn't immediately takeover over the top ecological niches the Non-Avian Dinosaurs left vacant. That is because many surviving reptile groups filled those voids first (albeit briefly). In many parts of the globe, The Paleocene was still the age of the reptiles. https://news.agu.org/press-release/scientists-reconstruct-ancient-impact-that-dwarfs-dinosaur-extinction-blast/ A Geologic Time Scale 2004. (2004). Nigeria: Cambridge University Press. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842625 This was partly due to the fact that the climate of the Paleocene and Eocene was generally hotter than today, which favored Ectothermic reptiles. As a result, these reptiles quickly grew to large body sizes and many filled the voids left vacant by the extinction of the endothermic non-avian theropod dinosaurs. Here is a list of these reptiles which hopefully demonstrates the diversity of these incredible creatures during the Paleocene. Let me know if I forgot any examples. North America - Thoracosaurus neocesariensis (Gavialoidea) (Late Cretaceous-Paleocene (70.6-56.0 Million Years ago)) (Note: Thoracosaurus species could grow up to 5 meters (16 feet) in length) Kosmodraco dakotensis (Choristodera) (Paleocene (60.2-56.8 Million Years ago) (Note: Kosmodraco dakotensis could grow up to 5 meters (16 feet) in length) Kosmodraco magnicornis (Choristodera) (Paleocene (56.8-55 Million Years ago)) Champsosaurus gigas (Choristodera) (Paleocene) (Note: Champsosaurus gigas could grow up to 3 meters (9 feet) in length) Borealosuchus acutidentatus (Crocodylomorpha) (Late Cretaceous-Paleocene (66.0-63.3 Million Years ago)) Axestemys splendida (Soft-shell turtle-Trionychidae) (Late Cretaceous-Paleocene) (Note: Axestemys species could grow up to 2 meters (6 feet) in length) Axestemys montinsana (Soft-shell turtle-Trionychidae) (Late Cretaceous-Paleocene) (Note: Axestemys species could grow up to 2 meters (6 feet) in length) Adocus onerosus (turtle-Dermatemyidae) (Paleocene) (Note: Adocus species could grow up to 80 cm. (2 feet) In length) Europe - Thoracosaurus isorhynchus (Gavialoidea) (Late Cretaceous-Paleocene (70.6-56.0 Million Years ago)) (Note: Thoracosaurus species could grow up to 5 meters (16 feet) in length) South America - Cerrejonisuchus improcerus (Dyrosaurid) (Mid-Late Paleocene (60-58 Million Years ago)) Acherontisuchus guajiraensis (Dyrosaurid) (Mid-Late Paleocene (60-58 Million Years ago)) Titanoboa cerrejonensis (Boa snake-Boidae) (Mid-Late Paleocene (60-58 Million Years ago)) (Note: Titanoboa cerrejonensis could grow up to 12.8 meters (42 feet) in length) Carbonemys cofrinii (turtle-Podocnemididae) (Mid-Late Paleocene (60-58 Million Years ago)) Cerrejonemys wayuunaiki (turtle-Podocnemididae) (Mid-Late Paleocene (60-58 Million Years ago)) (Note: Cerrejonemys wayuunaiki could have grown to 1 meter (3 feet) in length)) Puentemys mushaisaensis (turtle-Bothremydidae) (Mid-Late Paleocene (60-58 Million Years ago)) (Note: Puentemys mushaisaensis could have grown to 1.51 meters (5 feet) in length)) Africa - Arambourgisuchus khouribgaensis (Dyrosaurid) (Late Paleocene (59-55 Million Years ago)) Chenanisuchus lateroculi (Dyrosaurid) (Late Cretaceous-Paleocene) (Note: Chenanisuchus lateroculi could grow up to 4.5 meters (14 feet) in length) Amananulam sanogoi (aquatic snake-Nigerophiidae) (Paleocene) Acleistochelys maliensis (turtle-Bothremydidae) (Paleocene 61.7-55.8 Million Years ago) What do you guys think?