ResearchPad - prehistoric-animals https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[The fast and the frugal: Divergent locomotory strategies drive limb lengthening in theropod dinosaurs]]> https://www.researchpad.co/article/elastic_article_14509 Limb length, cursoriality and speed have long been areas of significant interest in theropod paleobiology, since locomotory capacity, especially running ability, is critical in the pursuit of prey and to avoid becoming prey. The impact of allometry on running ability, and the limiting effect of large body size, are aspects that are traditionally overlooked. Since several different non-avian theropod lineages have each independently evolved body sizes greater than any known terrestrial carnivorous mammal, ~1000kg or more, the effect that such large mass has on movement ability and energetics is an area with significant implications for Mesozoic paleoecology. Here, using expansive datasets that incorporate several different metrics to estimate body size, limb length and running speed, we calculate the effects of allometry on running ability. We test traditional metrics used to evaluate cursoriality in non-avian theropods such as distal limb length, relative hindlimb length, and compare the energetic cost savings of relative hindlimb elongation between members of the Tyrannosauridae and more basal megacarnivores such as Allosauroidea or Ceratosauridae. We find that once the limiting effects of body size increase is incorporated there is no significant correlation to top speed between any of the commonly used metrics, including the newly suggested distal limb index (Tibia + Metatarsus/ Femur length). The data also shows a significant split between large and small bodied theropods in terms of maximizing running potential suggesting two distinct strategies for promoting limb elongation based on the organisms’ size. For small and medium sized theropods increased leg length seems to correlate with a desire to increase top speed while amongst larger taxa it corresponds more closely to energetic efficiency and reducing foraging costs. We also find, using 3D volumetric mass estimates, that the Tyrannosauridae show significant cost of transport savings compared to more basal clades, indicating reduced energy expenditures during foraging and likely reduced need for hunting forays. This suggests that amongst theropods, hindlimb evolution was not dictated by one particular strategy. Amongst smaller bodied taxa the competing pressures of being both a predator and a prey item dominant while larger ones, freed from predation pressure, seek to maximize foraging ability. We also discuss the implications both for interactions amongst specific clades and Mesozoic paleobiology and paleoecological reconstructions as a whole.

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<![CDATA[Anatomy of the dinosaur Pampadromaeus barberenai (Saurischia—Sauropodomorpha) from the Late Triassic Santa Maria Formation of southern Brazil]]> https://www.researchpad.co/article/5c76fe1bd5eed0c484e5b4e9

Sauropodomorphs are the most abundant and diverse clade of Triassic dinosaurs, but the taxonomy of their earliest (Carnian) representatives is still poorly understood. One such taxon is Pampadromaeus barberenai, represented by a nearly complete disarticulated skeleton recovered from the upper part of the Santa Maria Formation of Rio Grande do Sul, Brazil. Here, the osteology of Pam. barberenai is fully described for the first time. Detailed comparisons with other Carnian sauropodomorphs reveal a unique anatomy, corroborating its status as a valid species. Potential autapomorphies of Pam. barberenai can be seen in the articulation of the sacral zygapophyses, the length of the pectoral epipodium, the shape of the distal articulation of the femur and the proximal articulation of metatarsal 1. A novel phylogenetic study shows that relationships among the Carnian sauropodomorphs are poorly constrained, possibly because they belong to a “zone of variability”, where homoplasy abounds. Yet, there is some evidence that Pam. barberenai may nest within Saturnaliidae, along with Saturnalia tupiniquim and Chromogisaurus novasi, which represents the sister group to the larger sauropodomorphs, i.e. Bagualosauria.

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<![CDATA[The braincase of Malawisaurus dixeyi (Sauropoda: Titanosauria): A 3D reconstruction of the brain endocast and inner ear]]> https://www.researchpad.co/article/5c6dca27d5eed0c48452a84d

A braincase of the Cretaceous titanosaurian sauropod Malawisaurus dixeyi, complete except for the olfactory region, was CT scanned and a 3D rendering of the endocast and inner ear was generated. Cranial nerves appear in the same configuration as in other sauropods, including derived features that appear to characterize titanosaurians, specifically, an abducens nerve canal that passes lateral to the pituitary fossa rather than entering it. Furthermore, the hypoglossal nerve exits the skull via a single foramen, consistent with most titanosaurians, while other saurischians, including the basal titanosauriform, Giraffatitan, contain multiple rootlets. The size of the vestibular labyrinth is smaller than in Giraffatitan, but larger than in most derived titanosaurians. Similar to the condition found in Giraffatitan, the anterior semicircular canal is larger than the posterior semicircular canal. This contrasts with more derived titanosaurians that contain similarly sized anterior and posterior semicircular canals, congruent with the interpretation of Malawisaurus as a basal titanosaurian. Measurements of the humerus of Malawisaurus provide a body mass estimate of 4.7 metric tons. Comparison of body mass to radius of the semicircular canals of the vestibular labyrinth reveals that Malawisaurus fits the allometric relationship found in previous studies of extant mammals and Giraffatitan brancai. As in Giraffatitan, the anterior semicircular canal is significantly larger than is predicted by the allometric relationship suggesting greater sensitivity and slower movement of the head in the sagittal plane.

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<![CDATA[A new African Titanosaurian Sauropod Dinosaur from the middle Cretaceous Galula Formation (Mtuka Member), Rukwa Rift Basin, Southwestern Tanzania]]> https://www.researchpad.co/article/5c6dca2ad5eed0c48452a874

The African terrestrial fossil record has been limited in its contribution to our understanding of both regional and global Cretaceous paleobiogeography, an interval of significant geologic and macroevolutionary change. A common component in Cretaceous African faunas, titanosaurian sauropods diversified into one of the most specious groups of dinosaurs worldwide. Here we describe the new titanosaurian Mnyamawamtuka moyowamkia gen. et sp. nov. from the Mtuka Member of the Galula Formation in southwest Tanzania. The new specimen preserves teeth, elements from all regions of the postcranial axial skeleton, parts of both appendicular girdles, and portions of both limbs including a complete metatarsus. Unique traits of M. moyowamkia include the lack of an interpostzygapophyseal lamina in posterior dorsal vertebrae, pronounced posterolateral expansion of middle caudal centra, and an unusually small sternal plate. Phylogenetic analyses consistently place M. moyowamkia as either a close relative to lithostrotian titanosaurians (e.g., parsimony, uncalibrated Bayesian analyses) or as a lithostrotian and sister taxon to Malawisaurus dixeyi from the nearby Aptian? Dinosaur Beds of Malawi (e.g., tip-dating Bayesian analyses). M. moyowamkia shares a few features with M. dixeyi, including semi-spatulate teeth and a median lamina between the neural canal and interpostzygapophyseal lamina in anterior dorsal vertebrae. Both comparative morphology and phylogenetic analyses support Mnyamawamtuka as a distinct and distant relative to Rukwatitan bisepultus and Shingopana songwensis from the younger Namba Member of the Galula Formation with these results largely congruent with newly constrained ages for the Mtuka Member (Aptian–Cenomanian) and Namba Member (Campanian). Coupled with recent discoveries from the Dahkla Oasis, Egypt (e.g., Mansourasaurus shahinae) and other parts of continental Afro-Arabia, the Tanzania titanosaurians refine perspectives on the development of African terrestrial faunas throughout the Cretaceous—a critical step in understanding non-marine paleobiogeographic patterns of Africa that have remained elusive until the past few years.

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<![CDATA[A new baby oviraptorid dinosaur (Dinosauria: Theropoda) from the Upper Cretaceous Nemegt Formation of Mongolia]]> https://www.researchpad.co/article/5c648cf4d5eed0c484c81b9d

Recent discoveries of new oviraptorosaurs revealed their high diversity from the Cretaceous Period in Asia and North America. Particularly, at the family level, oviraptorids are among the most diverse theropod dinosaurs in the Late Cretaceous of Mongolia and China. A new oviraptorid dinosaur Gobiraptor minutus gen. et sp. nov. from the Upper Cretaceous Nemegt Formation is described here based on a single holotype specimen that includes incomplete cranial and postcranial elements. The most prominent characters of Gobiraptor are its thickened rostrodorsal end of the mandibular symphysis and a rudimentary lingual shelf on each side of the dentary. Each lingual shelf is lined with small occlusal foramina and demarcated by a weakly developed lingual ridge. This mandibular morphology of Gobiraptor is unique among oviraptorids and likely to be linked to a specialized diet that probably included hard materials, such as seeds or bivalves. The osteohistology of the femur of the holotype specimen indicates that the individual was fairly young at the time of its death. Phylogenetic analysis recovers Gobiraptor as a derived oviraptorid close to three taxa from the Ganzhou region in southern China, but rather distantly related to other Nemegt oviraptorids which, as the results of recent studies, are also not closely related to each other. Gobiraptor increases diversity of oviraptorids in the Nemegt Formation and its presence confirms the successful adaptation of oviraptorids to a mesic environment.

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<![CDATA[Cranial Anatomy and Palaeoneurology of the Archosaur Riojasuchus tenuisceps from the Los Colorados Formation, La Rioja, Argentina]]> https://www.researchpad.co/article/5989db3bab0ee8fa60bd4fa9

Riojasuchus tenuisceps Bonaparte 1967 is currently known from four specimens, including two complete skulls, collected in the late 1960s from the upper levels of the Los Colorados Formation (Late Triassic), La Rioja, Argentina. Computed tomography (CT) scans of the skulls of the holotype and a referred specimen of Riojasuchus tenuisceps and the repreparation of the latter allows recognition of new features for a detailed analysis of its cranial anatomy and its comparison with a wide variety of other archosauriform taxa. The diagnosis of Riojasuchus tenuisceps is emended and two autapomorphies are identified on the skull: (1) a deep antorbital fossa with its anterior and ventral edges almost coinciding with the same edges of the maxilla itself and (2) a suborbital fenestra equal in size to the palatine-pterygoid fenestra. Also, the first digital 3D reconstruction of the encephalon of Riojasuchus tenuisceps was carried out to study its neuroanatomy, showing a shape and cranial nerve disposition consistent to that of other pseudosuchians.

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<![CDATA[If Dung Beetles (Scarabaeidae: Scarabaeinae) Arose in Association with Dinosaurs, Did They Also Suffer a Mass Co-Extinction at the K-Pg Boundary?]]> https://www.researchpad.co/article/5989d9f0ab0ee8fa60b6e0f4

The evolutionary success of beetles and numerous other terrestrial insects is generally attributed to co-radiation with flowering plants but most studies have focused on herbivorous or pollinating insects. Non-herbivores represent a significant proportion of beetle diversity yet potential factors that influence their diversification have been largely unexamined. In the present study, we examine the factors driving diversification within the Scarabaeidae, a speciose beetle family with a range of both herbivorous and non-herbivorous ecologies. In particular, it has been long debated whether the key event in the evolution of dung beetles (Scarabaeidae: Scarabaeinae) was an adaptation to feeding on dinosaur or mammalian dung. Here we present molecular evidence to show that the origin of dung beetles occurred in the middle of the Cretaceous, likely in association with dinosaur dung, but more surprisingly the timing is consistent with the rise of the angiosperms. We hypothesize that the switch in dinosaur diet to incorporate more nutritious and less fibrous angiosperm foliage provided a palatable dung source that ultimately created a new niche for diversification. Given the well-accepted mass extinction of non-avian dinosaurs at the Cretaceous-Paleogene boundary, we examine a potential co-extinction of dung beetles due to the loss of an important evolutionary resource, i.e., dinosaur dung. The biogeography of dung beetles is also examined to explore the previously proposed “out of Africa” hypothesis. Given the inferred age of Scarabaeinae as originating in the Lower Cretaceous, the major radiation of dung feeders prior to the Cenomanian, and the early divergence of both African and Gondwanan lineages, we hypothesise that that faunal exchange between Africa and Gondwanaland occurred during the earliest evolution of the Scarabaeinae. Therefore we propose that both Gondwanan vicariance and dispersal of African lineages is responsible for present day distribution of scarabaeine dung beetles and provide examples.

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<![CDATA[Redescription and Phylogenetic Analysis of the Mandible of an Enigmatic Pennsylvanian (Late Carboniferous) Tetrapod from Nova Scotia, and the Lability of Meckelian Jaw Ossification]]> https://www.researchpad.co/article/5989da30ab0ee8fa60b844ac

The lower jaw of an unidentified Pennsylvanian (Late Carboniferous) tetrapod from Nova Scotia – the “Parrsboro jaw”- is redescribed in the light of recent tetrapod discoveries and work on evolution of tetrapod mandibular morphology and placed for the first time in a numerical cladistics analysis. All phylogenetic analyses place the jaw in a crownward polytomy of baphetids, temnospondyls, and embolomeres. Several features resemble baphetids and temnospondyls including dermal ornamentation, absence of coronoid teeth, and presence of coronoid shagreen. Dentary dentition is most similar to Baphetes. An adsymphysial toothplate may not preclude temnospondyl affinity. An apparent large exomeckelian fenestra, with the dorsal foraminal margins formed by an unossified element, echoes the morphology of the stem tetrapod Sigournea and is unusually primitive given the other features of the jaw. The jaw may thus provide an example of an intermediate stage in Meckelian element evolution.

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<![CDATA[Phylogenetic Relationships of the Triassic Archaeosemionotus Deecke (Halecomorphi, Ionoscopiformes) from the ‘Perledo Fauna’]]> https://www.researchpad.co/article/5989db44ab0ee8fa60bd7da2

The lagerstätten in the Monte San Giorgio have provided excellent fossils representing one of the most important windows to the marine life during the Triassic. Among these fossils, fishes are abundant and extraordinarily well preserved. Most of these fishes represent extinct lineages and were difficult to understand and classify during the early years after discovery. These difficulties usually led to a mixture of species under the same taxonomic name. This is the case of fishes referred to the genus Archaeosemionotus. The name bearing type of A. connectens, the type species of this genus, represents a basal halecomorph, but most other fishes referred to this genus represent basal ginglymodians. Therefore, we conducted this study to clarify the taxonomic status and phylogenetic relationships of A. connectens, which is a member of the family Furidae (Halecomorphi, Ionoscopiformes) representing the second cladistically supported evidence of ionoscopiforms in the Triassic and it is thus one of the two oldest reliable records of this group. Ionoscopiforms have a long stratigraphic range, though their fossil record is rather patchy. In our analysis, the sister taxon of Archaeosemionotus is Robustichthys from the Anisian of China, and they together form a clade with Furo, which is known from several localities ranging from the Early to the Late Jurassic. Other ionoscopiforms are so far known from the Kimmeridgian to the Albian and it is thus evident that recent efforts have concentrated on the later history of the group (Late Jurassic to Cretaceous). The phylogenetic relationships obtained for the Ionoscopiformes do not show a clear palaeobiogeographic pattern, but give important new insights into the origin, divergence date and early history of this clade.

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<![CDATA[PLoS Biology Issue Image | Vol. 16(3) March 2018]]> https://www.researchpad.co/article/5ae424c4463d7e02f65f0b93

Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary

Pterosaurs were winged cousins of the dinosaurs and lived from around 200 million years ago to 66 million years ago, when the last pterosaurs disappeared during the Cretaceous-Paleogene extinction that wiped out the dinosaurs. The pterosaurs are thought to have declined in diversity before their final extinction, suggesting that gradual processes played a major role in their demise. However, this study by Longrich et al. describes hundreds of new pterosaur fossils from the end of the Cretaceous in Morocco, including as many as seven species. These represent three different families and show substantial variation in size and skeletal proportions, suggesting that they occupied a wide range of ecological niches. The image shows an artist's impression of diverse pterosaurs flying over the Moroccan coast 66 million years ago.

Image Credit: John Conway

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<![CDATA[Novel insight into the origin of the growth dynamics of sauropod dinosaurs]]> https://www.researchpad.co/article/5989db5fab0ee8fa60be1254

Sauropod dinosaurs include the largest terrestrial animals and are considered to have uninterrupted rapid rates of growth, which differs from their more basal relatives, which have a slower cyclical growth. Here we examine the bone microstructure of several sauropodomorph dinosaurs, including basal taxa, as well as the more derived sauropods. Although our results agree that the plesiomorphic condition for Sauropodomorpha is cyclical growth dynamics, we found that the hypothesized dichotomy between the growth patterns of basal and more derived sauropodomorphs is not supported. Here, we show that sauropod-like growth dynamics of uninterrupted rapid growth also occurred in some basal sauropodomorphs, and that some basal sauropods retained the plesiomorphic cyclical growth patterns. Among the sauropodomorpha it appears that the basal taxa exploited different growth strategies, but the more derived Eusauropoda successfully utilized rapid, uninterrupted growth strategies.

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<![CDATA[Where to Dig for Fossils: Combining Climate-Envelope, Taphonomy and Discovery Models]]> https://www.researchpad.co/article/5989da39ab0ee8fa60b8724e

Fossils represent invaluable data to reconstruct the past history of life, yet fossil-rich sites are often rare and difficult to find. The traditional fossil-hunting approach focuses on small areas and has not yet taken advantage of modelling techniques commonly used in ecology to account for an organism’s past distributions. We propose a new method to assist finding fossils at continental scales based on modelling the past distribution of species, the geological suitability of fossil preservation and the likelihood of fossil discovery in the field, and apply it to several genera of Australian megafauna that went extinct in the Late Quaternary. Our models predicted higher fossil potentials for independent sites than for randomly selected locations (mean Kolmogorov-Smirnov statistic = 0.66). We demonstrate the utility of accounting for the distribution history of fossil taxa when trying to find the most suitable areas to look for fossils. For some genera, the probability of finding fossils based on simple climate-envelope models was higher than the probability based on models incorporating current conditions associated with fossil preservation and discovery as predictors. However, combining the outputs from climate-envelope, preservation, and discovery models resulted in the most accurate predictions of potential fossil sites at a continental scale. We proposed potential areas to discover new fossils of Diprotodon, Zygomaturus, Protemnodon, Thylacoleo, and Genyornis, and provide guidelines on how to apply our approach to assist fossil hunting in other continents and geological settings.

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<![CDATA[A New Centrosaurine Ceratopsid, Machairoceratops cronusi gen et sp. nov., from the Upper Sand Member of the Wahweap Formation (Middle Campanian), Southern Utah]]> https://www.researchpad.co/article/5989db3dab0ee8fa60bd586a

The Upper Cretaceous (middle-late Campanian) Wahweap Formation of southern Utah contains the oldest diagnostic evidence of ceratopsids (to date, all centrosaurines) in North America, with a number of specimens recovered from throughout a unit that spans between 81 and 77 Ma. Only a single specimen has been formally named, Diabloceratops eatoni, from the lower middle member of the formation. Machairoceratops cronusi gen. et sp. nov., a new centrosaurine ceratopsid from the upper member of the Wahweap Formation, is here described based on cranial material representing a single individual recovered from a calcareous mudstone. The specimen consists of two curved and elongate orbital horncores, a left jugal, a nearly complete, slightly deformed braincase, the left squamosal, and a mostly complete parietal ornamented by posteriorly projected, anterodorsally curved, elongate spikes on either side of a midline embayment. The fan-shaped, stepped-squamosal is diagnostic of Centrosaurinae, however, this element differs from the rectangular squamosal in Diabloceratops. Machairoceratops also differs in the possession of two anterodorsally (rather than laterally) curved epiparietal ornamentations on either side of a midline embayment that are distinguished by a posteromedially-oriented sulcus along the entire length of the epiparietal. Additionally, the parietosquamosal frill is lacking any other epiossifications along its periphery. Machairoceratops shares a triangular (rather than round) frill and spike-like epiparietal loci (p1) ornamentation with the stratigraphically lower Diabloceratops. Both parsimony and Bayesian phylogenetic analyses place Machairoceratops as an early-branching centrosaurine. However, the parsimony-based analysis provides little resolution for the position of the new taxon, placing it in an unresolved polytomy with Diabloceratops. The resultant Bayesian topology yielded better resolution, aligning Machairoceratops as the definitive sister taxon to a clade formed by Diabloceratops and Albertaceratops. Considered together, both phylogenetic methods unequivocally place Machairoceratops as an early-branching centrosaurine, and given the biostratigraphic position of Machairoceratops, these details increase the known ceratopsid diversity from both the Wahweap Formation and the southern portion of Laramidia. Finally, the unique morphology of the parietal ornamentation highlights the evolutionary disparity of frill ornamentation near the base of Centrosaurinae.

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<![CDATA[The “χ” of the Matter: Testing the Relationship between Paleoenvironments and Three Theropod Clades]]> https://www.researchpad.co/article/5989da40ab0ee8fa60b89d6c

The view of spinosaurs as dinosaurs of semi-aquatic habits and strongly associated with marginal and coastal habitats are deeply rooted in both scientific and popular knowledge, but it was never statistically tested. Inspired by a previous analysis of other dinosaur clades and major paleoenvironmental categories, here we present our own statistical evaluation of the association between coastal and terrestrial paleoenvironments and spinosaurids, along with other two theropod taxa: abelisaurids and carcharodontosaurids. We also included a taphonomic perspective and classified the occurrences in categories related to potential biases in order to better address our interpretations. Our main results can be summarized as follows: 1) the taxon with the largest amount of statistical evidence showing it positively associated to coastal paleoenvironments is Spinosauridae; 2) abelisaurids and carcharodontosaurids had more statistical evidence showing them positively associated with terrestrial paleoenvironments; 3) it is likely that spinosaurids also occupied spatially inland areas in a way somehow comparable at least to carcharodontosaurids; 4) abelisaurids may have been more common than the other two taxa in inland habitats.

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<![CDATA[Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians]]> https://www.researchpad.co/article/5989da42ab0ee8fa60b8a8ab

We describe two new cynodonts from the early Late Triassic of southern Brazil. One taxon, Bonacynodon schultzi gen. et sp. nov., comes from the lower Carnian Dinodontosaurus AZ, being correlated with the faunal association at the upper half of the lower member of the Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina). Phylogenetically, Bonacynodon is a closer relative to Probainognathus jenseni than to any other probainognathian, bearing conspicuous canines with a denticulate distal margin. The other new taxon is Santacruzgnathus abdalai gen. et sp. nov. from the Carnian Santacruzodon AZ. Although based exclusively on a partial lower jaw, it represents a probainognathian close to Prozostrodon from the Hyperodapedon AZ and to Brasilodon, Brasilitherium and Botucaraitherium from the Riograndia AZ. The two new cynodonts and the phylogenetic hypothesis presented herein indicate the degree to which our knowledge on probainognathian cynodonts is incomplete and also the relevance of the South American fossil record for understanding their evolutionary significance. The taxonomic diversity and abundance of probainognathians from Brazil and Argentina will form the basis of deep and complex studies to address the evolutionary transformations of cynodonts leading to mammals.

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<![CDATA[New Material of the Pterosaur Gladocephaloideus Lü et al., 2012 from the Early Cretaceous of Liaoning Province, China, with Comments on Its Systematic Position]]> https://www.researchpad.co/article/5989d9e9ab0ee8fa60b6c42c

Although there are nine genera of ctenochasmatoids reported from the Jehol Biota, at present each is known from a specimen that has either a skull or a relatively complete postcranial skeleton. A nearly complete juvenile specimen of Gladocephaloideus from the Lower Cretaceous Jiufotang Formation of Sihedang, Lingyuan of Liaoning Province is the most complete ctenochasmatoid preserved to date with a skull and postcranial skeleton. Based on the holotype (IG-CAGS 08–07) and the nearly complete new specimen (JPM 2014–004), the diagnosis of Gladocephaloideus is amended: approximately 50 teeth in total with sharp tips; small nasoantorbital opening, occupying approximately 13% of total skull length; ratio of prenarial rostrum length to skull length approximately 0.63; deep groove along the mid-line of the mandibular symphysis; length to width ratio of the longest cervical vertebra = 4.1; ratio of femur length to tibia length = 0.61; tibia as long as the wing-phalange 1. Phylogenetic analysis recovers Gladocephaloideus within the clade Ctenochasmatidae. Gladocephaloideus has a closer relationship to the Chinese Pterofiltrus rather than to other ctenochasmatid pterosaurs. Microstructure of limb bones implies that JPM 2014–004 represents an early juvenile of Gladocephaloideus jingangshanensis, and that the type specimen is not a fully grown specimen either. We assume that the holotype may equate to the late juvenile or sub-adult developmental stage of Gladocephaloideus.

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<![CDATA[The African cynodont Aleodon (Cynodontia, Probainognathia) in the Triassic of southern Brazil and its biostratigraphic significance]]> https://www.researchpad.co/article/5989db5fab0ee8fa60be107e

In this contribution we report the first occurrence of the enigmatic African probainognathian genus Aleodon in the Middle-early Late Triassic of several localities from the state of Rio Grande do Sul in southern Brazil. Aleodon is unusual among early probainognathians in having transversely-expanded postcanine teeth, similar to those of gomphodont cynognathians. This genus was previously known from the Manda Beds of Tanzania and the upper Omingonde Formation of Namibia. The Brazilian record of this genus is based upon multiple specimens representing different ontogenetic stages, including three that were previously referred to the sectorial-toothed probainognathian Chiniquodon theotonicus. We propose a new species of Aleodon (A. cromptoni sp. nov.) based on the specimens from Brazil. Additionally, we tentatively refer one specimen from the upper Omingonde Formation of Namibia to this new taxon, strengthening biostratigraphic correlations between these strata. Inclusion of A. cromptoni in a phylogenetic analysis of eucynodonts recovers it as the sister-taxon of A. brachyrhamphus within the family Chiniquodontidae. The discovery of numerous specimens of Aleodon among the supposedly monospecific Chiniquodon samples of Brazil raises concerns about chiniquodontid alpha taxonomy, particularly given the extremely broad geographic distribution of Chiniquodon. The discovery of Brazilian Aleodon and new records of the traversodontid Luangwa supports the hypothesis that at least two subzones can be recognized in the Dinodontosaurus Assemblage Zone.

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<![CDATA[Species Identification of Archaeological Skin Objects from Danish Bogs: Comparison between Mass Spectrometry-Based Peptide Sequencing and Microscopy-Based Methods]]> https://www.researchpad.co/article/5989d9d7ab0ee8fa60b661df

Denmark has an extraordinarily large and well-preserved collection of archaeological skin garments found in peat bogs, dated to approximately 920 BC – AD 775. These objects provide not only the possibility to study prehistoric skin costume and technologies, but also to investigate the animal species used for the production of skin garments. Until recently, species identification of archaeological skin was primarily performed by light and scanning electron microscopy or the analysis of ancient DNA. However, the efficacy of these methods can be limited due to the harsh, mostly acidic environment of peat bogs leading to morphological and molecular degradation within the samples. We compared species assignment results of twelve archaeological skin samples from Danish bogs using Mass Spectrometry (MS)-based peptide sequencing, against results obtained using light and scanning electron microscopy. While it was difficult to obtain reliable results using microscopy, MS enabled the identification of several species-diagnostic peptides, mostly from collagen and keratins, allowing confident species discrimination even among taxonomically close organisms, such as sheep and goat. Unlike previous MS-based methods, mostly relying on peptide fingerprinting, the shotgun sequencing approach we describe aims to identify the complete extracted ancient proteome, without preselected specific targets. As an example, we report the identification, in one of the samples, of two peptides uniquely assigned to bovine foetal haemoglobin, indicating the production of skin from a calf slaughtered within the first months of its life. We conclude that MS-based peptide sequencing is a reliable method for species identification of samples from bogs. The mass spectrometry proteomics data were deposited in the ProteomeXchange Consortium with the dataset identifier PXD001029.

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<![CDATA[A Basal Tapejarine (Pterosauria; Pterodactyloidea; Tapejaridae) from the Crato Formation, Early Cretaceous of Brazil]]> https://www.researchpad.co/article/5989da38ab0ee8fa60b86f17

A three-dimensional and almost complete pterosaur mandible from the Crato Formation (Early Cretaceous of Northeastern Brazil), Araripe Basin, is described as a new species of a tapejarine tapejarid. Tapejarines are a particular group of toothless pterosaurs, characterized by well-developed cranial crests, downturned rostra, and have been proposed to represent frugivorous flying reptiles. Though comparatively well represented and distributed, the evolutionary history of the group is still poorly known, and the internal relationships of its members are not well understood. The new species here reported, named Aymberedactylus cearensis gen. et sp. nov., adds new data concerning the evolution of the group, concerning their morphology and geographical origin. It differs from known tapejarids due to its unusually elongate retroarticular process and a shallow fossa on the splenial exhibiting distinctive rugose texture. Furthermore, it exhibits a suite of basal and derived conditions within the Tapejaridae, demonstrating how their morphological traits probably evolved and that these forms were even more diverse than already acknowledged. The discovery of Aymberedactylus cearensis sheds new light on the evolutionary history of the Tapejarinae.

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<![CDATA[A New Specimen of the Controversial Chasmosaurine Torosaurus latus (Dinosauria: Ceratopsidae) from the Upper Cretaceous Hell Creek Formation of Montana]]> https://www.researchpad.co/article/5989da24ab0ee8fa60b8022e

Torosaurus latus is an uncommon and contentious taxon of chasmosaurine ceratopsid known from several upper Maastrichtian units in western North America. We describe a partial parietal of To. latus from the Hell Creek Formation of Montana. Although the specimen’s ontogenetic maturity means that it cannot inform the ongoing debate over whether To. latus is the old adult form of the contemporary Triceratops, the specimen is one of the best-preserved To. latus parietals and supplements previous descriptions.

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