Search the Community

The Eumaniraptora is a clade of non-avian theropod dinosaurs that first emerged during the late Jurassic period and diversified extensively during the subsequent Cretaceous period (143-66 Million years ago). This group is most famously known as the Raptor dinosaurs (the sister clade of the theropod dinosaurs that gave direct rise to the birds), consisting of mostly small to mid sized theropod dinosaurs. There are a few species though that exceed the typical small-medium size range for the raptor dinosaurs. Only a few giant raptor dinosaurs are currently known. But recent discoveries over the past few decades have demonstrated large raptor dinosaurs were less of an exception in Cretaceous ecosystems than previously thought. Here is a list of all the currently known giant Eumaniraptora from the fossil record which hopefully can expand our understanding the vital roles these animals played in the ecosystems they once inhabited. Let me know if I forgot any examples. South America Austroraptor cabazai (Dromaeosauridae - Argentina, South America) (Late Cretaceous (78-66 Million Years ago)) (grew up to 6 meters (20 feet) in length) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2679073/ Antarctica Imperobator antarcticus (Eumaniraptora - part of what is now James Ross Island, Antarctica) (Late Cretaceous (71 Million Years ago)) (grew up to 4 meters (13 feet) in length, note: did not have the iconic pair of sickle shaped claw on its feet like most other Eumaniraptora) https://www.sciencedirect.com/science/article/abs/pii/S0195667118300120?via%3Dihub Asia Achillobator giganticus (Dromaeosauridae - part of what is now Mongolia, Asia) (Late Cretaceous (96-89 Million Years ago)) (grew up to 5 meters (16 feet) in length) Perle, A.; Norell, M. A.; Clark, J. M. (1999). "A new maniraptoran Theropod−Achillobator giganticus (Dromaeosauridae)−from the Upper Cretaceous of Burkhant, Mongolia". Contributions from the Geology and Mineralogy Chair, National Museum of Mongolia (101): 1−105. Unnamed Bissekty Formation Giant Dromaeosauridae (Dromaeosauridae (could possible be a species of Itemirus) - part of what is now Uzbekistan, Asia) (Late Cretaceous (92-90 Million Years ago)) (based on Specimens CCMGE 600/12457, ZIN PH 11/16, grew up to 5.5 meters (18 feet) in length) https://www.researchgate.net/publication/263891965_Dromaeosauridae_Dinosauria_Theropoda_from_the_Bissekty_Formation_Upper_Cretaceous_Turonian_of_Uzbekistan_and_the_phylogenetic_position_of_Itemirus_medullaris_Kurzanov_1976 https://www.cambridge.org/core/journals/geological-magazine/article/abs/giant-dromaeosaurid-theropod-from-the-upper-cretaceous-turonian-bissekty-formation-of-uzbekistan-and-the-status-of-ulughbegsaurus-uzbekistanensis/4543ABAB1EC19C84405EDF66A5F53124 Europe Unnamed Wessex Formation Giant Dromaeosauridae (Dromaeosauridae (specimens for this species could belong to Vectiraptor) - Isle of Wight, Great Britain, Europe) (Early Cretaceous (125 Million Years ago)) (based on Specimens IWCMS.2002.1, IWCMS.2002.3, IWCMS.2002.4., and BMNH R 16510, grew up to 5.5 meters (18 feet) in length) https://www.researchgate.net/publication/222830089_The_first_record_of_velociraptorine_dinosaurs_Saurischia_Theropoda_from_the_Wealden_Early_Cretaceous_Barremian_of_southern_England https://www.sciencedirect.com/science/article/abs/pii/S0195667121003712 Unnamed Giant Dromaeosauridae (Dromaeosauridae - Gorodishchenskii District Russia, Europe) (Late Cretaceous (72.1-66.0 Million Years ago)) (based on Specimen VGI. no. 231/2, grew up to 5.8 meters (19 feet) in length) https://www.researchgate.net/publication/235806763_Carnivorous_dinosaurs_Saurischia_Theropoda_from_the_Maastrichtian_of_the_Volga-Don_Interfluve_Russia North America Utahraptor ostrommaysi (Dromaeosauridae - Western North America) (Early Cretaceous (135-130 Million Years ago)) (grew up to 5.5 meters (18 feet) in length) https://www.researchgate.net/publication/285714464_A_large_dromaeosaur_Theropoda_from_the_Lower_Cretaceous_of_eastern_Utah Dakotaraptor steini (Dromaeosauridae - Western North America) (Late Cretaceous (66 Million years ago)) (grew up to 5.5 meters (18 feet) in length) https://www.researchgate.net/publication/283655219_The_first_giant_raptor_Theropoda_Dromaeosauridae_from_the_Hell_Creek_Formation Unnamed Marshalltown Formation Giant Dromaeosauridae (Dromaeosauridae - Eastern North America) (Late Cretaceous (72.1 Million Years ago)) (based on Specimen NJSM 14158, grew up to 5.5 meters (18 feet) in length) https://www.researchgate.net/publication/327117985_The_distinctive_theropod_assemblage_of_the_Ellisdale_site_of_New_Jersey_and_its_implications_for_North_American_dinosaur_ecology_and_evolution_during_the_Cretaceous https://terpconnect.umd.edu/~gdouglas/raptor/index.html Unnamed Tar Heel Formation Giant Dromaeosauridae ((Dromaeosauridae - Eastern North America) (Late Cretaceous (78.5-77.1 Million Years ago)) (Based on Specimen YPM.VPPU.021397, grew up to 3.4 meters (11 feet 2 inches) in length) https://peerj.com/preprints/26829/ Alaska Troodontid (Troodontidae (could be a species of Troodon or a new genus in Troodontidae) - Prince Creek Formation Alaska, Western North America) (Late Cretaceous (70.6-69.1 Million Years ago) (grew up to almost 4 meters (13 feet) in length) https://www.researchgate.net/publication/236632883_On_the_Occurrence_of_Exceptionally_Large_Teeth_of_Troodon_Dinosauria_Saurischia_from_the_Late_Cretaceous_of_Northern_Alaska Latenivenatrix mcmasterae (Troodontidae - Dinosaur Park Formation, Alberta Canada, Western North America) (Late Cretaceous (75.5 Million years ago)) (grew up to 3.5 meters (11.5 feet) in length) https://tspace.library.utoronto.ca/bitstream/1807/78296/1/cjes-2017-0031.pdf Unnamed Mount Laurel Formation Giant Dromaeosauridae (Dromaeosauridae - Eastern North America) (Late Cretaceous (72.1 Million Years ago)) (based on Specimen NJSM GP 22949, grew up to 3.4 meters (11 feet 2 inches) in length) https://royalsocietypublishing.org/doi/10.1098/rsos.191206 What do you guys think?

Hi! I'm a new user who's really into marine reptile bones, by which I mean mosasaurs and plesiosaurs from the Late Cretaceous strata found where I live. I've recently found a small yet satisfying piece that seems to be a hollow bone of a pterosaur/bird. The age of the strata is Late Campanian/Early Mastrichtian and the rock itself is an erratic piece of an "opoka" - a siliceous limestone typically found in Poland and Germany. The bedrock from which it originates lies very likely underneath the Quarternary cover in what is now the Gdańsk Bay (SE Baltic Sea region). It's hollow inside and when viewed with a 60x magnification LAGs and Haversian Canals are visible. Is it likely to be a bone of some tetrapod, say pterosaur/bird? Or might it come from a fish? (that is, if fish actually posses hollow bones, which I might be not aware of yet). Any answers will be very much appreciated. Excuse me for any writing mistakes, which I might make, I'm not any native English speaker. If any more photos are needed I'll send them right away. Cheers, Simon

I've recently found a, how do I say...quite unusual Theropod dinosaur tooth from the Late Cretaceous Hell Creek Formation (67-66.0 Million Years ago). The paper, titled The occurrences of vertebrate fossils in the Deadhorse Coulee Member of the Milk River Formation and their implications for provincialism and evolution in the Santonian (Late Cretaceous) of North America by Derek Williams Larson, is a record of theropod teeth from various Late Cretaceous formations in Western North America, and buried on page 244 of the report an apparent megalosauridae tooth (UCMP120305) from the Hell Creek Formation (67-66.0 Million Years ago). https://era.library.ualberta.ca/items/54e305be-de2a-4529-adc9-4e6b038ae699/view/28ba15f8-8131-44be-b48f-e4e9648db26e/Larson_Derek_Fall_2010.pdf This for me is pretty unusual as Megalosauridae (as far as we know) lived only between the Middle-Late Jurassic (170-145 Million Years ago), millions of years before the Maastrichtian Cretaceous. I know in the past many theropod dinosaurs were described as species of "Megalosaurus", but that was more around the 1800-early 1900s and the citation for the tooth lists its apparent phylogenetic description as recently as 2008. There was also another less confusing but fascinating description of a Dromaeosauridae tooth (UALVP48462) from the Milk River Formation, which apparently has a tooth crown height of 17.3mm. But besides the pretty fascinating Milk River Dromeosauridae tooth, I'm puzzled about the UCMP120305 specimen! I really skeptical this tooth specimen belongs to megalosauridae. But if it's not, then where could the classification of the specimen have come from? What do you guys think?

The two most prominent hypothesizes on the direct evolutionary origin of perhaps the most famous Theropod Dinosaur from the fossil record, Tyrannosaurus Rex (Tyrannosauridae, Late Cretaceous (68-66 Million Years ago)) are what I call the Laramidia and Asian Origins. The Laramidia origin (named after the region of the Western North America which was a separate Continent during most of the Late Cretaceous and home to a vast amount of dinosaurs including Tyrannosaurus rex) hypothesizes that Tyrannosaurus rex is the direct descendent of and evolved from slightly older North American Tyrannosaurids like Daspletosaurus (Tyrannosauridae, Late Cretaceous (79.5-74 Million Years ago)). Warshaw, Elías & Fowler, Denver. (2022). A transitional species of Daspletosaurus Russell, 1970 from the Judith River Formation of eastern Montana. PeerJ. 10. e14461. 10.7717/peerj.14461. https://www.researchgate.net/publication/365746599_A_transitional_species_of_Daspletosaurus_Russell_1970_from_the_Judith_River_Formation_of_eastern_Montana The Asian origin hypothesizes that Tyrannosaurus’s direct ancestor was a Tyrannosaurid from Asia. This supported by how closely related the Asian Tyrannosaurid Tarbosaurus (Tyrannosauridae, Late Cretaceous (70 Million Years ago)). This hypothesis further elaborates that a that the Asian Tyrannosaurids arrived in Western North America via a land bridge between what is now Eastern Russia and Alaska around 73-72 Million Years ago. On arrival, theses Asian Tyrannosaurids outcompeted and caused the extinction of most of the Native Tyrannosaur species of Laramidia (including Albertosaurus (Tyrannosaurid, Late Cretaceous (71-68 Million Years ago)), creating conditions allowing for the emergence of the genus Tyrannosaurus. Brusatte, Stephen & Carr, Thomas. (2016). The phylogeny and evolutionary history of tyrannosauroid dinosaurs. Scientific Reports. 6. 20252. 10.1038/srep20252. https://www.nature.com/articles/srep20252 Takasaki R, Fiorillo AR, Tykoski RS, Kobayashi Y (2020) Re-examination of the cranial osteology of the Arctic Alaskan hadrosaurine with implications for its taxonomic status. PLoS ONE 15(5): e0232410. https://doi.org/10.1371/journal.pone.0232410 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0232410 Both hypotheses have points that are supported by the fossil record, but still don’t fill all the gaps in answering the question of the direct origin of the genus Tyrannosaurus. There is however another hypothesis I have pondered over for at least the past few months which could fill in some (if not all) the gaps to this question. It is the Hybrid Speciation Origin hypothesis. The Hybrid Speciation Origin hypothesis basically states that after a land bridge formed between Eurasia and Laramidia during the Late Campanian stage of the Cretaceous (73-72 Million Years ago) and the Asian Tyrannosaurids arrived in Laramidia, certain individuals of a Asian Tyrannosaurid genus breed with a species of a genus of Native Laramidia Tyrannosaurid (likely a direct descendent of Daspletosaurus). Enough of these inter-genus breeding events occurred that a new Tyrannosaurid genus distinct from its parent species (and genuses) emerged around 68 Million Years ago, Tyrannosaurus. I will admit this would be extremely difficult to prove, but I do believe it could be a valid hypothesis. It corroborates the many similarities in skeletal structure Tyrannosaurus shares (and how closely related it is phylogenetically) with the Asian Tyrannosaurid Tarbosaurus and the skeletal structure similarities and general body shape it shares with Daspletosaurus. Image Credit: https://www.nature.com/articles/srep20252 Brusatte, Stephen & Carr, Thomas. (2016). The phylogeny and evolutionary history of tyrannosauroid dinosaurs. Scientific Reports. 6. 20252. 10.1038/srep20252. https://www.nature.com/articles/srep20252 Warshaw, Elías & Fowler, Denver. (2022). A transitional species of Daspletosaurus Russell, 1970 from the Judith River Formation of eastern Montana. PeerJ. 10. e14461. 10.7717/peerj.14461. https://www.researchgate.net/publication/365746599_A_transitional_species_of_Daspletosaurus_Russell_1970_from_the_Judith_River_Formation_of_eastern_Montana Stein, Walter W.; Triebold, Michael (2013). "Preliminary Analysis of a Sub-adult Tyrannosaurid Skeleton from the Judith River Formation of Petroleum County, Montana". In J. Michael Parrish; Ralph E. Molnar; Philip J. Currie; Eva B. Koppelhus (eds.). Tyrannosaurid Paleobiology. Bloomington: Indiana University Press. pp. 55–77. Currie, P.J. (2003). Cranial anatomy of tyrannosaurid dinosaurs from the Late Cretaceous of Alberta, Canada. Acta Palaeontologica Polonica 48 (2): pp. 191–226. https://www.app.pan.pl/archive/published/app48/app48-191.pdf I am interested in how the tyrannosaurid species Nanuqusaurus (Tyrannosaurid, Late Cretaceous (70-68 (likely also to 66) Million years ago), the Daspletosaur Tyrannosaurid specimen RMDRC 2002.MT-001 “Sir William”, and the Tyrannosaurid specimen CM 9401 could factor into the validity of the hybrid speciation hypothesis. I hold no illusions in thinking this hypothesis is not going to be controversial. But I do think it could be semi plausible. What do you guys think?