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The Cretaceous landmass of Appalachia has preserved an understudied but nevertheless important record of dinosaurs that has recently come under some attention. In the past few years, the vertebrate faunas of several Appalachian sites have been described. One such locality, the Ellisdale site of the Cretaceous Marshalltown Formation of New Jersey, h...
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... proximal surface is semi- rectangular in shape, and there is no vertical inflection on the proximal articular facet. Measurements of this bone may be found in Table 1. NJSM 14682 is most parsimoniously placed within Tyrannosauroidea based on several features of the bone. ...
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... the author regards it as unlikely that NJSM 14682 comes from a deinocheirid, given that the group is currently only represented by Cretaceous genera from Asia (e.g., Lee et al., 2014). NJSM 14682 may further be distinguished from those of ornithomimids by the lack of proximally projecting ridges that extend past the proximal end of the bone and form a concavity on the ventral surface, a robust distal end that has approximately the same mediolateral width as the proximal (Table 1), having a deeper flexor fossa relative to the pedal phalanx III-1 of ornithomimosaurs, having a deeply concave proximal surface, and having a mediolaterally "pinched," as opposed to gently arched, diaphysis (e.g., Osborn, 1921, fig. 3a; Osmólska et al., 1972, fig. ...
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... 4 Description.-NJSM 14686 is smaller than NJSM 14682 in all dimensions (Table 1), measuring 67 mm long proximodistally. The bone is slightly eroded, though most of the bone surface is well preserved and not noticeably abraded. ...
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... dorsal and ventral views, the lateral and medial sur- faces are also gently arched and gently curved outward towards the proximal end in expansion. The proximal end is appreciably wider than the distal (Table 1), and the proximal end bears pointed processes on its ventral corners that form a shallow concavity ventrally. The proximal end, though not noticeably eroded, lacks a vertically oriented projection, and there is no rim surrounding the proximal articular facet. ...
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... Rather, the specimen is more similar to the pedal phalanges III of Harpymimus, Nedcolbertia, an ornithomimosaur from the Aptian-Albian of China, and of ornithomimosaurs from the Arundel Clay of Maryland in the extent of its proximally oriented ventral processes and the ratio between its dorsoventral height and mediolateral width proximally (e.g., Table 1; Gilmore, 1920;Kirkland et al., 1998;Shapiro et al., 2003;Kobayashi and Barsbold, 2005a). Thus, it may be that the specimen represents an ornithomimosaur species basal to those found in the west during the Campanian, a condition that has been found with other dinosaur groups on Appalachia (e.g., Schwimmer, 1997;Carr et al., 2005;Brusatte et al., 2010;Prieto-Márquez et al., 2016aPrieto-Márquez et al., , 2016b). ...
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Abstract We explore hypothetical ecologies to explain diversity among predatory dinosaurs in North America’s medial Cretaceous, based on occurrence, tooth morphology, and stable isotope analysis. The Mussentuchit local fauna, Utah, USA, is among the best-known terrestrial vertebrate assemblages from the Cretaceous. Study samples include teeth from...
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... Dromaeosaurids purportedly had a broad range of cranial morphology [10,11,24]. Different species also cohabitated in palaeoecosystems with diverse climates and environments [22,[25][26][27], implying diverse niches to limit competition with one another. ...
Non-avialan theropod dinosaurs had diverse ecologies and varied skull morphologies. Previous studies of theropod cranial morphology mostly focused on higher-level taxa or characteristics associated with herbivory. To better understand morphological disparity and function within carnivorous theropod families, here we focus on the Dromaeosauridae, ‘raptors’ traditionally seen as agile carnivorous hunters.
We applied 2D geometric morphometrics to quantify skull shape, performed mechanical advantage analysis to assess the efficiency of bite force transfer, and performed finite element analysis to examine strain distribution in the skull during biting. We find that dromaeosaurid skull morphology was less disparate than most non-avialan theropod groups. Their skulls show a continuum of form between those that are tall and short and those that are flat and long. We hypothesise that this narrower morphological disparity indicates developmental constraint on skull shape, as observed in some mammalian families. Mechanical advantage indicates that Dromaeosaurus albertensis and Deinonychus antirrhopus were adapted for relatively high bite forces, while Halszkaraptor escuilliei was adapted for high bite speed, and other dromaeosaurids for intermediate bite forces and speeds. Finite element analysis indicates regions of high strain are consistent within dromaeosaurid families but differ between them. Average strain levels do not follow any phylogenetic pattern, possibly due to ecological convergence between distantly-related taxa.
Combining our new morphofunctional data with a re-evaluation of previous evidence, we find piscivorous reconstructions of Halszkaraptor escuilliei to be unlikely, and instead suggest an invertivorous diet and possible adaptations for feeding in murky water or other low-visibility conditions. We support Deinonychus antirrhopus as being adapted for taking large vertebrate prey, but we find that its skull is relatively less resistant to bite forces than other dromaeosaurids. Given the recovery of high bite force resistance for Velociraptor mongoliensis, which is believed to have regularly engaged in scavenging behaviour, we suggest that higher bite force resistance in a dromaeosaurid taxon may reflect a greater reliance on scavenging rather than fresh kills.
Comparisons to the troodontid Gobivenator mongoliensis suggest that a gracile rostrum like that of Velociraptor mongoliensis is ancestral to their closest common ancestor (Deinonychosauria) and the robust rostra of Dromaeosaurus albertensis and Deinonychus antirrhopus are a derived condition. Gobivenator mongoliensis also displays a higher jaw mechanical advantage and lower resistance to bite force than the examined dromaeosaurids, but given the hypothesised ecological divergence of troodontids from dromaeosaurids it is unclear which group, if either, represents the ancestral condition. Future work extending sampling to troodontids would therefore be invaluable and provide much needed context to the origin of skull form and function in early birds. This study illustrates how skull shape and functional metrics can discern non-avialan theropod ecology at lower taxonomic levels and identify variants of carnivorous feeding.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12862-024-02222-5.
... This, together with the observation that this assemblage consists of mixed terrestrial, freshwater, and marine faunal elements, suggests that the fossiliferous beds at White Owl may represent a condensed section resulting from a short-lived transgressive event in an otherwise overall sea-level regression associated with the retreat of WIS waters at the close of the Cretaceous and the development of the Dakota Isthmus (Erickson, 1978(Erickson, , 1999. Similar mixed assemblages deriving in part from short term transgressive events, are known from the Atlantic Coastal Plain, such as in the Campanian Black Creek Group of North Carolina (Schwimmer, 1997) and the Campanian Marshalltown Formation at Ellisdale, New Jersey (Brownstein, 2018). Such occurrences are known also from the WIS, as in the case of the Campanian Dinosaur Park Formation of Alberta (Eberth, 1996;Eberth & Brinkman, 1997). ...
... Both specimens therefore come from a time when the fossil record of Laramidian ornithomimids is relatively impoverished. In this, the Fox Hills discovery mirrors similar low abundances of contemporary ornithomimids on the Appalachian side of the Western Interior Seaway (e.g., Brownstein, 2018;Chinzorig et al., 2022). ...
We report here the first dinosaur skeletal material described from the marine Fox Hills Formation (Maastrichtian) of western South Dakota. The find consists of two theropod pedal phalanges: one recovered from the middle part of the Fairpoint Member in Meade County, South Dakota; and the other from the Iron Lightning Member in Ziebach County, South Dakota. Comparison with pedal phalanges of other theropods suggests strongly that the Fairpoint specimen is a right pedal phalanx, possibly III-2, from a large ornithomimid. The Iron Lightning specimen we cautiously identify as an ornithomimid left pedal phalanx II-2. The Fairpoint bone comes from thinly bedded and cross-bedded marine sandstones containing large hematitic concretions and concretionary horizons. Associated fossils include osteichthyan teeth, fin spines and otoliths, and abundant teeth of common Cretaceous nearshore and pelagic chondrichthyans. Leaf impressions and other plant debris, blocks of fossilized wood, and Ophiomorpha burrows are also common. The Iron Lightning bone comes from a channel deposit composed of fine to coarse sandstone beds, some of which contain bivalves, and a disseminated assemblage of mammal teeth, chondrichthyan teeth, and fragmentary dinosaur teeth and claws. We interpret the depositional environment of the two specimens as marginal marine. The Fairpoint bone derives from a nearshore foreset setting, above wave base subject to tidal flux and storm activity. The Iron Lightning specimen comes from a topset channel infill probably related to deposition on a tidal flat or associated coastal setting. The taphonomic history and ages of the two bones differ. Orthogonal cracks in the cortical bone of the Fairpoint specimen suggest post-mortem desiccation in a dryland coastal setting prior to transport and preservation in the nearby nearshore setting described above. The pristine surface of the Iron Lightning specimen indicates little transport before incorporation into the channel deposit in which it was found. The Fairpoint bone bed most probably lies within the Hoploscaphites nicolletii Ammonite Zone of the early late Maastrichtian, and would therefore have an approximate age of 69 Ma. The Iron Lightning bone is from the overlying H. nebrascensis Ammonite Zone, and is thus about one million years younger.
... Fossils of Deinosuchus have also been recovered from the Black Creek Formation of North Carolina, which is between 80 and 71 Ma (see Fig. 4.6 in Schwimmer (2002)); however, Schwimmer (2002) reported that eastern Deinosuchus appear to go extinct in the southeastern United States by about 77 Ma. Finally, Deinosuchus is also reported from the Marshalltown Formation of New Jersey (Schwimmer, 2002), which dates to between 79.6 and 76.4 Ma (Denton & Tashjian, 2012;Brownstein, 2018). ...
The neosuchian Deinosuchus is known from numerous localities throughout the Campanian of North America, from New Jersey to Montana (USA) and as far south as Coahuila (Mexico). Here we describe six osteoderms, two vertebrae, and a partial tooth discovered in the Menefee Formation of New Mexico and assign them to Deinosuchus sp., representing one of the earliest occurrences of this genus on the Laramidian subcontinent, and among the earliest known occurrences of this large alligatoroid in all of North America. The osteoderms are morphologically distinct in their inflated construction, with deep and radially distributed pitting, which closely matches osteoderms of Deinosuchus. Subjects Evolutionary Studies, Paleontology
... The formation of large epicontinental seas clearly has the potential to split ancestral ranges in multiple lineages causing a single biota to evolve into two or more distinct biotas. This effect is clearly observed in the theropod dinosaur faunas of the Campian (Upper Cretaceous) of North America following the formation of the Western Interior Seaway (Brownstein 2018). The diverse theropod fauna of the Atlantic Coastal Plain was similar to that of western regions of North America during the mid-Cretaceous but by the Campian was distinct. ...
Neotectonics has undergone incredible development since Vladimir Obruchev proposed the term in 1948. With the discovery of mid-oceanic ridges, subduction, mantle flow, and dynamic topography, neotectonics has become the forefront of tectonic research. This chapter attempts to unite two fields, neotectonics and bioregionalisation, the latter being a result of the former.
... The formation of large epicontinental seas clearly has the potential to split ancestral ranges in multiple lineages causing a single biota to evolve into two or more distinct biotas. This effect is clearly observed in the theropod dinosaur faunas of the Campian (Upper Cretaceous) of North America following the formation of the Western Interior Seaway (Brownstein 2018). The diverse theropod fauna of the Atlantic Coastal Plain was similar to that of western regions of North America during the mid-Cretaceous but by the Campian was distinct. ...
Australia is the flattest continent on Earth and has a wide range of different landforms, making it an ideal place to investigate the impact of neotectonics (continental tilting and dynamic topography) on bioregionalisation. It is highly likely that continental tilting and dynamic uplift together have driven the biogeography of Australia since the Palaeogene.
... The formation of large epicontinental seas clearly has the potential to split ancestral ranges in multiple lineages causing a single biota to evolve into two or more distinct biotas. This effect is clearly observed in the theropod dinosaur faunas of the Campian (Upper Cretaceous) of North America following the formation of the Western Interior Seaway (Brownstein 2018). The diverse theropod fauna of the Atlantic Coastal Plain was similar to that of western regions of North America during the mid-Cretaceous but by the Campian was distinct. ...
We investigate some exemplar regions where the integration of neotectonics and dynamic topography had created unique biogeographic areas, namely, transition zones. We also term two new concepts, Marginal Plate Biotectonics and Intra-plate Biotectonics, to distinguish between different types of tectonic and biogeographic interactions. A preliminary analysis reveals that transitions zones along tectonic margins (subduction, transverse) share greater similarity to each other than they do with those found within plates. We also propose a case for biotectonic extinction and discuss the future of biotectonics.
... The formation of large epicontinental seas clearly has the potential to split ancestral ranges in multiple lineages causing a single biota to evolve into two or more distinct biotas. This effect is clearly observed in the theropod dinosaur faunas of the Campian (Upper Cretaceous) of North America following the formation of the Western Interior Seaway (Brownstein 2018). The diverse theropod fauna of the Atlantic Coastal Plain was similar to that of western regions of North America during the mid-Cretaceous but by the Campian was distinct. ...
We discuss the Australides, the orogenic belt that covers eastern Australia, New Zealand, East and West Antarctica, the Cape region of Africa, and South America, and summarize its tectonic history since the Neoproterozoic. A biotic analysis using palaeodistributional data is used to determine relationships between areas within the Australides. We integrate the palaeobiogeographic (phylogenetic) and tectonic histories in order to establish the extent in space and time of any Weddellian Province, and undertake an analysis of phylogenetic data (cladograms) to determine whether area relationships are driven by tectonostratigraphic terranes or by cratons and cratonic basins.
... The dimensions of this pedal phalanx are much longer than those of any other ornithomimosaur known for the Cretaceous of North America (e.g. Osborn, 1917;DeCourten and Russell, 1985;Brownstein, 2018;Hunt and Quinn, 2018) (see Table 2). ...
... Although, the phalangeal proportions of Paraxenisaurus normalensis look similar to those reported for tyrannosaurids and some tyrannosauroids (e.g. Brochu, 2003;Carr et al., 2005;Brownstein, 2018), this could be related to the large body-size (~5.7 m) and heavier bodyweight (~600 kg) that this dinosaur had to bear. This is the case for ornithomimosaurs Beishanlong grandis (Makovicky et al., 2010) and Deinocheirus mirificus (Lee et al., 2014), which had estimated body lengths of~5.9 m and 11 m, and estimated body weights of 626 kg and 6358 kg, respectively. ...
... In contrast, the pedal phalanges seen in tyrannosaurids and some tyrannosauroids are mediolaterally pinched, lack the proximally projecting processes and are more elongated (e.g. Brochu, 2003;Carr et al., 2005;Brownstein, 2018;Zanno et al., 2019). ...
New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation of Coahuila, Mexico is described herein. The material includes postcraneal elements from several individuals, which are assigned to a new genus and species, Paraxenisaurus normalensis. This new taxon is characterized by the presence of a strongly curved and laterally compressed manual ungual I with a distally placed flexor tubercle divided by a deep sulcus and a deeply concave proximal, elliptical-shaped articular surface; a metacarpal III that has an expanded proximal articular end, which is similar in width to metacarpal II; a combination of posterior caudal vertebrae, where the most anterior vertebrae possess low dorsoventral prezygapophyses with nearly vertical articulation surfaces, while the most posterior vertebrae have prezygapophyses that face ventromedially; a non-arctometatarsalian pes, where the proximal end of metatarsal III is expanded and has a proximal ovoid outline; the presence of an attachment site for pedal digit I in the posterior surface of the distal quarter of metatarsal II; an expanded medial condyle of metatarsal II; a transversely wide distal end of metatarsal III, which has a semi-ginglymoid articular surface; distinctively broad and ventrally curved pedal unguals that depending on the digit, the proximodorsal process changes its position adopting a lip-shaped appearance; a rounded, large foramen on the medial side of each pedal ungual and the presence of a deep ventral fossa that surrounds a strongly developed, ridge-like flexor tubercle. This combination of characteristics separate Paraxenisaurus normalensis from other ornithomimosaurs previously described in North America and in other parts of the world. Phylogenetic analysis shows that within Ornithomimosauria, Paraxenisaurus normalensis is recovered as a deinocheirid ornithomimosaur, along with Garudimimus brevipes and Deinocheirus mirificus. Therefore, the finding of Paraxenisaurus normalensis in the Cerro del Pueblo Formation of Coahuila, Mexico represents the first record of the Deinocheiridae family in the Campanian of North America.
... The formation of large epicontinental seas clearly has the potential to split ancestral ranges in multiple lineages causing a single biota to evolve into two or more distinct biotas. This effect is clearly observed in the theropod dinosaur faunas of the Campian (Upper Cretaceous) of North America following the formation of the Western Interior Seaway (Brownstein 2018). The diverse theropod fauna of the Atlantic Coastal Plain was similar to that of western regions of North America during the mid-Cretaceous but by the Campian was distinct. ...
Tectonic plates are constantly moving, either crashing into one another creating a mosaic of mountains and shallow seas, or tearing apart and isolating large swathes of land. In both cases plate tectonics separates populations leading to the evolution of biota. Tectonics is also responsible for the destruction life, for instance when large coral reefs or shallow seas are compressed to form mountain peaks. Could recent research into these processes provide enough evidence to show that tectonics may be the ultimate driver of life on Earth?
Our book delves into the current research in tectonics, particularly neotectonics, and its impact on rapid changes on biogeographical classification, also known as bioregionalisation. We also introduce a new term biotectonics that studies the impact of tectonics on biogeoregionalisation. The question we ask is how tectonics directly influences the distribution of biota in four case studies: the Mesozic and early Palaeogene Australides, which spans the Proto-Pacific coast of the South America, Antaractica and Australiasia; and the Neogene of Australia. To conclude we examine the role of neotectonics on tranistion zones and the Amazon Basin and make a case for biotectonic extinction.
... ALMNH 2001.1 is less recurved than NJSM GP 22949 and far less elongate in labial and lingual views (see [47]). Some saurornitholestine teeth from South Carolina [18] also lack the slender condition in NJSM GP 22949, where the mesiodistal width of the heavily recurved tooth crown is [41,48]. However, large crowns from Ellisdale are not 'slender' like NJSM GP 22949, are larger in size and bear distal denticles that are considerably more apically hooked than the Mt Laurel tooth and western saurornitholestines [48]. ...
... Some saurornitholestine teeth from South Carolina [18] also lack the slender condition in NJSM GP 22949, where the mesiodistal width of the heavily recurved tooth crown is [41,48]. However, large crowns from Ellisdale are not 'slender' like NJSM GP 22949, are larger in size and bear distal denticles that are considerably more apically hooked than the Mt Laurel tooth and western saurornitholestines [48]. A dromaeosaurid tooth from North Carolina is slightly larger than NJSM GP 22949, but is less recurved and far less slender [46]. ...
The faunal changes that occurred in the few million years before the Cretaceous-Palaeogene extinction are of much interest to vertebrate palaeontologists. Western North America preserves arguably the best fossil record from this time, whereas terrestrial vertebrate fossils from the eastern portion of the continent are usually limited to isolated, eroded postcranial remains. Examination of fragmentary specimens from the American east, which was isolated for the majority of the Cretaceous as the landmass Appalachia, is nonetheless important for better understanding dinosaur diversity at the end of the Mesozoic. Here, I report on two theropod teeth from the Mount Laurel Formation, a lower-middle Maastrichtian unit from northeastern North America. One of these preserves in detail the structure of the outer enamel and resembles the dentition of the tyrannosauroid Dryptosaurus aquilunguis among latest Cretaceous forms in being heavily mediolaterally compressed and showing many moderately developed enamel crenulations. Along with previously reported tyrannosauroid material from the Mt Laurel and overlying Cretaceous units, this fossil supports the presence of non-tyrannosaurid tyrannosauroids in the Campanian-Maastrichtian of eastern North America and provides evidence for the hypothesis that the area was still home to relictual vertebrates through the end of the Mesozoic. The other tooth is assignable to a dromaeosaurid and represents both the youngest occurrence of a non-avian maniraptoran in eastern North America and the first from the Maastrichtian reported east of the Mississippi. This tooth, which belonged to a 3-4 m dromaeosaurid based on size comparisons with the teeth of taxa for which skeletons are known, increases the diversity of the Maastrichtian dinosaur fauna of Appalachia. Along with previously reported dromaeosaurid teeth, the Mt Laurel specimen supports the presence of mid-sized to large dromaeosaurids in eastern North America throughout the Cretaceous.
