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The Tyrannosaur Dinosaurs (Tyrannosauroidea) inhabited North America from 152 Million Years ago during the Late Jurassic era up until 66 Million Years ago during the Late Cretaceous era. https://www.app.pan.pl/article/item/app20110141.html However, there is a relatively large geologic gap between the time of the Late Jurassic to the Santonian-Campanian stages of the Cretaceous (when the the oldest known Tyrannosaurid Lythronax (Late Creteaceous, 81.9-81.5 Million Years ago) emerged) in terms of the number of Tyrannosauroidae confirmed in North America. However, this doesn't mean they were completely absent from the Continent. Rather, they remained small to mid sized predators under the shadow of Large Carnosaurs up until the Cenomanian-Turnonian extinction event 93-94 Million years ago, which the tyrannosaurs filled the role of Apex Predator in most terrestrial ecosystems by the Campanian stage of the Cretaceous. The Tyrannosaur geologic gap between the Late Jurassic and Santonian Cretaceous is also not completely empty and several confirmed Tyrannosauroidea are known from this time period in North America. I've created a list of known Tyrannosauroidea species and specimens from the Aptian-Santonian Cretaceous of North America which I would like to share on the fourtm (let me know if there are any examples I'm missing or should add): Unnamed Cloverly Formation Tyrannosauroid (Tyrannosaur – Cloverly Formation, Wyoming, US, North America) (Early Cretaceous, 108 Million Years ago) (Based on Specimen FMNH PR 2750, likely grew up to 1.2 meters (3.9 feet) in length) https://www.tandfonline.com/doi/abs/10.1080/08912963.2010.543952 https://www.researchgate.net/profile/Lindsay- Zanno/publication/229287579_On_the_earliest_record_of_Cretaceous_tyrannosauroids_in_western_North_America_Implications_for_an_Early_Cretaceous_Laurasian_interchange_event/links/0fcfd50089dd8f3955000000/On-the-earliest-record-of-Cretaceous-tyrannosauroids-in-western-North-America-Implications-for-an-Early-Cretaceous-Laurasian-interchange-event.pdf Unnamed Wayan Formation Tyrannosauroid (Tyrannosaur – Wayan Formation, Idaho, US, North America) (Early Late Cretaceous, 100.6-97.8 Million Years ago) (Based on Specimen IMNH 2251/53975, grew up to 1.2 meters (3.9 feet) in length) https://bioone.org/journals/journal-of-paleontology/volume-96/issue-6/jpa.2022.42/A-partial-tyrannosauroid-femur-from-the-mid-Cretaceous-Wayan-Formation/10.1017/jpa.2022.42.full Unnamed Lewisville Formation Tyrannosauroid (Tyrannosaur - Woodbine Group Lewisville Formation, Texas US, North America) (Late Cretaceous (100-95 Million Years ago)) (Based on Specimens DMNH 2013-0701701 and SMU 77218, grew up to 2.7-4.8 meters (8.8-15 feet) in length) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8796713/ Moros intrepidus (Tyrannosaur – Cedar Mountain Formation, Utah, US, North America) (Early Cretaceous (96.4 Million Years ago)) (Grew up to 1.2 meters (3.9 feet) in length) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6385174/ Suskityrannus hazelae (Tyrannosaur – Moreno Hill Formation, New Mexico, US, North America) (Early Cretaceous, 93.5-89.3 Million Years ago) (grew up to 3 meters (9.8 feet) in length) https://www.pure.ed.ac.uk/ws/files/82474043/82473554._Brusatte._AAM.pdf

Hello everyone! I have recently been working on a project which includes precisely identifying shark teeth from the Campanian of the middle east. digging in the literature just made it clear that its REALLY messy. There is one promising resource however - Henri Capetta's guide to all mesozoic elasmobranch teeth. Does anybody here have the book or know someone who may have a copy? It would be a TREMENDOUS help! Book: Cappetta H. Chondrichtyes II. Mesozoic and Cenozoic Elasmobranchii: teeth Handbook of Paleoichthyology 3E, second edition,Schweizerbart, Stuttgart, 1–193, 2012. Here are some images of the finds, Welcome to share ideas on them too Dolev

Along with an interest in Pennsylvanian fish diversity, I've also had an interest (like many others studying Paleontology) in the diversity of Dinosaur genera during the Cretaceous era (particularly the Theropod diversity in North America during the Maastrichtian period 72.1-66 Million years ago). Compared to the preceding Campanian period (83.6-72.1 Million years ago), I've noticed there is a slightly less number of known Tyannosauridae genera in Western North America (at the time a separate continent known as Laramidia). I've come up with a list of confirmed known and possible Tyrannosauridae genera during the Maastrichtian period in Western North America and Eastern North America. Eastern North America (at the time a separate continent known as Appalachia) Dryptosaurus Donoho Creek Formation Tyrannosauridae genera (possibly Appalachiosaurus) https://palaeo-electronica.org/content/2018/2123-appalachia-biogeography Chronister well (Ripley Formation) Tyrannosauridae genera 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 Western North America (Laramidia) Tyrannosaurus Rex Nanuqsaurus (Prince Creek Formation) Albertosaurus (more early Maastrichtian to around 68 Million Years ago) ?"Alamotyrannus" (could also be a species of Tyrannosaurus - ?Tyrannosaurus brinkmani) ?"Daspletosaurus sp. (Horseshoe Canyon Formation) (specimen CMN 11315) (more early Maastrichtian to around 68 Million Years ago) https://cdnsciencepub.com/doi/10.1139/cjes-2014-0072 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7079176/ I'm wondering if this is an accurate list, why is there a dip in Tyrannosauridae diversity in Eastern and Western North America after the Campanian (was it a result of the Deccan Volcanic eruptions in India around the same time, at least for Western North America (if this theory is current) the Native Western North American Tyrannosaur genera being outcompeted by the Eurasian ancestors of Tyrannosaurus Rex arriving in North America via a land bridge during the late Campanian Early Maastrichtian, or both), the status on the taxonomic validity of Alamotyrannus, was Nanuqusaurus present during the later part of the Maastrichtian, and did Albertosaurus and Tyrannosaurus Rex ever come into direct contact with one another?

A while back, I was researching the number of likely Tyrannosauroidea dinosaurs that inhabited the Southern Hemisphere (I know this is a very controversial subject) in the Early Cretaceous for an extra credit research paper I was doing for my freshmen year college geology class. As I was looking for data for the paper, I found an unusual data entry on the paleontological database website fossilworks.org - It lists Tyrannosauridae remains from Jurassic Madagascar. http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&collection_no=55391 The specimen MSNM V5819 (consisting of a partial tooth) was apparently found in Mahajanga, Madagascar at the Bathonian aged Isalo Illb Formation (dating 167.7-164.7 million years ago) in 2003. S. Maganuco, A. Cau, and G. Pasini (2005) First description of theropod remains from the Middle Jurassic (Bathonian) of Madagascar. Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, 146(2):165-202 https://www.researchgate.net/publication/257651210_First_description_of_theropod_remains_from_the_Middle_Jurassic_Bathonian_of_Madagascar (You can read the actual paper with this above link). Here is also two photographs from the paper of the specimen MSNM V5819 The authors of the paper (which I must say did a really good job with the research and paper itself) state that a healthy degree of caution must be given in assigning MSNM V5819 to Tyrannosauroidea. Still, if this is indeed correct, It would be one of the earliest members of Tyrannosauroidea, with the only currently known older Tyrannosauroidea taxon being Proceratosaurus of England. The Specimen MSNM V5819 is maybe even older than Kileskus of Russia, Guanlong of China, and Aviatyrannus of Portugal. Still, the only currently known specimen is a single tooth, MSNM V5819, and I'm not 100% certain this represents a member of Tyrannosauroidea? What do you guys think?

Greetings! This is my first share on this forum. I was looking through my collections, and one thing popped my mind was this tooth -- a tooth of Xiongguanlong baomoensis，which i found in 2014 but I could not give a very conclusive identification until earlier this year. I was lucky enough to travel along with a group of scientists into the Gobi desert in Northern China. That day we was traveling in the border zone of three different provinces, basically middle of nowhere. This basin is where most dinosaur from Gansu found -- including X. baomoensis, Auroraceratop rugosus, Lanzhousaurus magnidens, etc. I found two dozen of borken teeth on a random hill. In the beginning I thought those teeth could be either iguanadon, hadrosaurus or some crocodilians. After collecting them and bringing them back to Beijing, I went focusing on other real-life project (preparing for college, preparing for grad-school, etc.). It became a memory sealed in attic and lost until I was re-examining the crocodilian fossils I found from the same trip. Then my eyes fell on this tooth, which I recalled seeing similar teeth from the Lanzhou Geological Mesuem and labelled X. baimoensis. After a further comparing with other teeth from the same clade in museums in China, I am certain that this tooth could belongs to X. baomoensis. X. baomoensis is one of the most mysterious member of the superfamily Tyrannosauroidea, and only thing I could be sure that they could grow larger than the specimen preserved in Lanzhou -- for I found a large theropodian matatarsal from the same site and it's certainly larger than the skeleton they demonstrates. I put it somewhere in my mountains of boxes, please allows me some time to look for it.

We managed to get out to the NJ brooks today after two weeks of heavy rains, we wanted to try out a new spot we hadn't been to before in the brook and the results did not disappoint! We wound up with a good assortment of quality specimens including many teeth taking their place in our collection as the highest quality/largest - total tripmakers! We were immediately met by a doe on the trail down, Luck? one may think After we picked a suitable spot to settle in and sift, this came up in the first scoop Immediately followed by this Happy with our spot, we sat and sifted for the day - the day's haul (grid is 1" x 1") Tripmaker teeth, our best/largest Crow shark (Squalicorax pristodontus) so far, largest Goblin (Scapanorhynchus texanus) anterior, and best/largest Goblin (Scapanorhynchus texanus) lateral. Unsure what the tooth between the Goblins is, leaning towards a Mackrel By far and away the most curious set of finds. These pieces came up in the same spot over the course of a couple of hours, I'm sure they're all fragments of a crab/lobster/ghost shrimp claw yet the coloration is different on all 3. Either way pretty cool My first vert, though only a frag, thinking some sort of bony fish Finally, mystery bone frag - possibly Pleistocene given the coloration/weight?

I know the cretaceous period ended 65-66 million years ago but when exactly did it end? Did it end as soon as the meteor touched the Earth's surface? As soon as all dinosaurs went extinct? After a certain amount of species went extinct? There may not be a definitive answer but if it was up to you where would you decide where the end of the cretaceous meets the beginning of the paleogene?