The cranial anatomy of the long-snouted tyrannosaurid dinosaur Qianzhousaurus sinensis from the Upper Cretaceous of China

Journal of Vertebrate Paleontology, Journal Year: 2021, Volume and Issue: 41(4)

Published: July 4, 2021

Tyrannosaurid theropods topped the terrestrial food chain in North America and Asia during latest Cretaceous. Most tyrannosaurids, exemplified by Tyrannosaurus rex, had deep snouts, thick teeth, large jaw muscles that could generate high bite forces. They coexisted with a morphologically divergent group of long-snouted relatives, called alioramins. Qianzhousaurus sinensis, from Maastrichtian Ganzhou, China, is largest alioramin yet discovered, but has only been briefly described. Here we present detailed osteological description holotype cranium mandible Qianzhousaurus. We identify several new autapomorphic features genus, synapomorphies unite alioramins (Qianzhousaurus, Alioramus altai, remotus) as clade, including laterally projecting rugosity on jugal. clarify elongate skull involves lengthening anterior palate not premaxilla, reflected posterior bones lower jaw, even though (orbit lateral temporal fenestra) are proportionally similar to deep-skulled tyrannosaurids. show much variation among species consistent growth trends other A. remotus, represent different ontogenetic stages progressive maturity, across which signature nasal rugosites became less prominent. predict represents adult level maturity for alioramins, propose morphology indicates weaker than suggestive differences prey choice feeding style.

Language: Английский

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Large-bodied ornithomimosaurs inhabited Appalachia during the Late Cretaceous of North America

PLoS ONE, Journal Year: 2022, Volume and Issue: 17(10), P. e0266648 - e0266648

Published: Oct. 19, 2022

Reconstructing the evolution, diversity, and paleobiogeography of North America’s Late Cretaceous dinosaur assemblages require spatiotemporally contiguous data; however, there remains a spatial temporal disparity in data on continent. The rarity vertebrate-bearing sedimentary deposits representing Turonian–Santonian ecosystems, relatively sparse record dinosaurs from eastern portion continent, present persistent challenges for studies American evolution. Here we describe an assemblage ornithomimosaurian materials Santonian Eutaw Formation Mississippi. Morphological coupled with osteohistological growth markers suggest presence two taxa different body sizes, including one largest ornithomimosaurians known worldwide. regression predicts femoral circumference mass individuals similar to or greater than that large-bodied ornithomimosaurs, Beishanlong grandis , Gallimimus bullatus . paleoosteohistology MMNS VP-6332 demonstrates individual was at least ten years age (similar B [~375 kg, 13–14 old death]). Additional pedal elements share some intriguing features yet larger-body size closer Deinocheirus mirificus ornithomimosaur this region during time is consistent recent discoveries early-diverging, ornithomimosaurs mid-Cretaceous strata Laurasia ( Arkansaurus fridayi ). smaller taxon represented by tibia preserving seven cycles, indicators decreasing growth, belongs approaching somatic maturity, suggesting co-existence medium- America. provide key information diversity distribution Appalachian fit broader evidence multiple cohabiting species ecosystems Laurasia.

Language: Английский

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Description of the first definitive Corythosaurus (Dinosauria, Hadrosauridae) specimens from the Judith River Formation in Montana, USA and their paleobiogeographical significance

The Anatomical Record, Journal Year: 2022, Volume and Issue: 306(7), P. 1918 - 1938

Published: Oct. 23, 2022

Abstract Despite the long history of research in late Campanian Judith River Formation northern Montana, most vertebrate fossils are represented by fragmentary remains, making precise taxonomic identifications difficult. Contrary to this, partially contemporaneous Dinosaur Park Formation, Alberta, Canada is known for its tremendous fossil preservation, permitting rigorous studies dinosaur diversity, evolution, and biostratigraphy. Hadrosaurids comprise one abundant clades but affinities hadrosaurid specimens remain poorly understood Formation. Corythosaurus common and, date, has been restricted this formation. This study reports first definitive from which were discovered on two private ranches Montana. The attribution complete skeleton indicated by: wide crest‐snout angle, presence premaxilla‐nasal fontanelle, dorsoventrally expanded nasal, laterally exposed ophthalmic canal laterosphenoid, tall neural spines. A second specimen preserves a large ilium that can be positively identified as based associated skull, now hands. recovered Coal Ridge Member approximately time equivalent Thus, discovery extends biogeographic range genus establishes framework future interformational biostratigraphic Late Cretaceous faunas North America.

Language: Английский

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New biogeochemical insights into Mesozoic terrestrial paleoecology and evidence for omnivory in troodontid dinosaurs

Geological Society of America Bulletin, Journal Year: 2023, Volume and Issue: 136(7-8), P. 2689 - 2701

Published: Nov. 15, 2023

Abstract The Cretaceous paleocommunities of North America preserve a rich record biodiversity that suggests many species occupied narrow biogeographic ranges in comparison to their ecological equivalents extant systems. How taxa these systems partitioned niches and structured communities can be difficult determine from fossils alone, which has led variety hypotheses concerning diets habitat use. Here, we examine element ratios (Sr/Ca, Ba/Ca) the enamel suite co-occurring vertebrate sampled spatiotemporally constrained interval Oldman Formation Alberta, Canada, reconstruct trophic structure, use δ13C, δ18O, 87Sr/86Sr compositions test for niche partitioning among hadrosaurids, ceratopsids, ankylosaurs. We also previously proposed dietary troodontid theropods. In large ornithischians, find Ba/Ca Sr/Ca are consistent with herbivory, hadrosaurs distinct ceratopsids ankylosaurids ranges, pattern is indicative differences use/breadth, plant sources, feeding height. mammals, varanoid lizards, dromaeosaurids, tyrannosaurids gradient lower animal-dominant omnivorous faunivorous diets. Troodontids, have been variably hypothesized as either faunivorous, omnivorous, or herbivorous due unusual dentition, fall between those ornithischians dromaeosaurids. From multi-proxy data, interpret troodontids mixed-feeding plant-dominant omnivores. These proxies represent valuable tool understanding community ecology ecosystems hold enormous potential future research paleobiology.

Language: Английский

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The phylogenetic affinities and morphological peculiarities of the bird-like dinosaurBorogovia gracilicrusfrom the Upper Cretaceous of Mongolia

PeerJ, Journal Year: 2021, Volume and Issue: 9, P. e12640 - e12640

Published: Dec. 6, 2021

Borogovia gracilicrus is a small-bodied theropod dinosaur from the Maastrichtian (Upper Cretaceous) Nemegt Formation of southern Mongolia. The taxon based on single fragmentary specimen preserving only distal part hindlimbs. morphology shows peculiar combination features, some which are traditionally considered troodontid synapomorphies and others unusual for Troodontidae but shared with other maniraptoran clades. In particular, second toe B. differs troodontids in lacking features contribute to specialized ‘sickle-clawed’ toe, here termed ‘falciphoran condition’, dromaeosaurids paravians, such as strongly compressed falciform ungual. Phylogeny reconstructions intended explore affinities consistently support its referral within subclade including all Late Cretaceous taxa. placement not significantly affected by combinations hindlimb or homoplasy elements forming falciphoran condition. supported valid distinct troodontids, Tochisaurus Zanabazar . lack ungual, distinctive interpreted derived specialization among retention plesiomorphic condition non-paravian theropods.

Language: Английский

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GEOMETRIC MORPHOMETRIC APPROACH TO ESTABLISH PHYLOGENETIC AFFINITIES OF ENIGMATIC PTEROSAUR SPECIMENS FROM THE LOWER CRETACEOUS OF SOUTH KOREA

Acta Palaeontologica Romaniae, Journal Year: 2024, Volume and Issue: 20 (1), P. 77 - 86

Published: Feb. 11, 2024

Fragmentary but scientifically important pterosaur fossils have been reported in Lower Cretaceous strata such as the Jinju and Hasandong formations of South Korea. Recently, several large teeth a second wing phalanx found these suggested to affinities with Boreopteridae, clade which has so far only Yixian Formation China. Here, phylogenetic proposed boreopterid specimens are reassessed, using two-dimensional geometric morphometric shape analyses. The analyses Korean different morphospaces from Fm. boreopterids, plot them closer anhanguerians. An isolated does close Zhenyuanopterus longirostris morphospace defined by first two principal component axes, taxa lineages also plotted closely, or even closer. Thus, there seems be no clear evidence that belong tooth appear very those established members this clade. Therefore, hypothesis some can referred is here tentatively rejected.

Language: Английский

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Early Cretaceous Troodontine Troodontid (Dinosauria: Theropoda) from the Ohyamashimo Formation of Japan Reveals the Early Evolution of Troodontinae

Research Square (Research Square), Journal Year: 2024, Volume and Issue: unknown

Published: June 7, 2024

A new troodontid dinosaur, Hypnovenator sasayamaensis gen. et sp. nov., is described based on an articulated postcranial skeleton recovered from the fluvial deposits of Albian Ohyamashimo Formation Sasayama Group in Tambasasayama City, Hyogo Prefecture, Japan. Hypnovenator distinguished other troodontids by four autapomorphies and a combination additional features. Our phylogenetic analysis positions as oldest one most basal troodontines, forming monophyletic clade with Gobivenator mongoliensis. The discovery suggests that small-bodied maniraptorans sleeping posture were common not only environments volcanic eolian events or alluvial systems but also systems. Geometric morphometric manual unguals shows I III exhibit considerable morphological variation are functionally similar, which differs those non-troodontine troodontids, reflecting transition motion within Troodontinae. has mosaic features pes related to cursoriality. This study reveals asymmetrical arctometatarsus occurred Albian, some changes, such shorter digit IV than non-ungual phalanges digits roller joints weakly ginglymoid articulation, arose during early Late Cretaceous.

Language: Английский

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Occurrence of Centrosaurus apertus (Ceratopsidae: Centrosaurinae) in Saskatchewan, Canada, and expanded dinosaur diversity in the easternmost exposure of the Late Cretaceous (Campanian) Dinosaur Park Formation

Canadian Journal of Earth Sciences, Journal Year: 2024, Volume and Issue: 61(11), P. 1127 - 1155

Published: Oct. 28, 2024

Late Campanian terrestrial communities of western Canada are best known from the fluvial–paralic deposits Dinosaur Park Formation (DPF) in Provincial (DPP), Alberta. However, a growing list localities isolated DPF outcrops, outside DPP area, offers glimpse into palaeocommunities that evolved isochronously with biotas greater proximity to Western Interior Seaway. Over past decade, one such locality was explored along Lake Diefenbaker Saskatchewan Landing Park. The initial palaeoecological analysis this marginal marine community based on palynomorph and vertebrate microfossil diversity has laid foundation for current study its monodominant ceratopsian bonebed. latter resulted new occurrences Centrosaurus apertus elmisaurine Citipes elegans incomplete yet diagnostic specimens. is unequivocally identified by parietal bar bearing two prominent P1 P2 hooks, which expands geographical habitat range species most coastal environment DPF. Furthermore, presence suggests region closer age lower than uppermost DPP, at odds previous palynostratigraphic interpretation. faunal composition bonebed also supports widely distributed metacommunity across these deposits. This contribution demonstrates how evidence multiple spatial gradient, beyond temporal gradient available within alone, picture as potential model system biotic turnover response sea level rise geological scale.

Language: Английский

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First articulated ornithomimid specimens from the upper Maastrichtian Scollard Formation of Alberta, Canada

Journal of Vertebrate Paleontology, Journal Year: 2021, Volume and Issue: 41(5)

Published: Aug. 27, 2021

Despite an abundance of ornithomimid fossils from the Late Cretaceous Alberta, Canada, only isolated elements are known upper Maastrichtian Scollard Formation. Ornithomimus velox and Struthiomimus sedens two taxa recognized penecontemporaneous formations in U.S.A., but incomplete nature these specimens lack contemporary material Alberta creates a gap our understanding diversity during late North America. Here, I describe first diagnostic Formation central providing new information about taxonomic composition American ornithomimids Maastrichtian. The fossil, articulated forelimb, exhibits metacarpal ratios features manual unguals that support its referral to genus Ornithomimus. second associated hind limb, belongs large-bodied ornithomimid, based on characteristics pedal is assigned Struthiomimus. Based designations, stratigraphic ranges both extended Campanian Dinosaur Park through which constitutes more than 10 million years time. These offer knowledge unusually long range coupled with difficulty diagnosing either specimen species underscores need for review taxonomy.

Language: Английский

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Large-bodied ornithomimosaurs inhabited Appalachia during the Late Cretaceous of North America

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2022, Volume and Issue: unknown

Published: March 25, 2022

Abstract Reconstructing the evolution, diversity, and paleobiogeography of North America’s Late Cretaceous dinosaur assemblages requires spatiotemporally contiguous data; however, there remains a spatial temporal disparity in data on continent. The rarity vertebrate-bearing sedimentary deposits representing Turonian–Santonian ecosystems, relatively sparse record dinosaurs from eastern portion continent, present persistent challenges for studies American evolution. Here we describe an assemblage ornithomimosaurian materials Santonian Eutaw Formation Mississippi. Morphological coupled with osteohistological growth markers suggest presence two taxa different body sizes, including one largest ornithomimosaurians known worldwide. regression predicts femoral circumference mass individuals similar to or greater than that large-bodied ornithomimosaurs, Beishanlong grandis Gallimimus bullatus . paleohistology MMNS VP-6332 demonstrates individual was at least 11 years age (similar B. [∼375 kg, 13–14 old death]). Additional pedal elements share some intriguing features ornithomimosaurs yet larger-body size closer Deinocheirus mirificus ornithomimosaur this region during time is consistent recent discoveries early-diverging, mid-Cretaceous strata Laurasia ( Arkansaurus fridayi ). smaller taxon represented by tibia preserving seven cycles, indicators decreasing growth, belongs near reaching somatic maturity larger taxon, suggesting co-existence medium- America. provide key information diversity distribution Appalachian fit broader evidence multiple cohabiting species ecosystems Laurasia.

Language: Английский

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