Dinosaur

... on the discovery by one of us (SAH) of an associated right ulna and radius (FHSM VP-13985) of a nodosaurid dinosaur from the ... The abbreviations for institutions referred to in the text are: FHSM - Sternberg Museum of Natural History, Fort Hays State University, Hays, KS; KUVP ...

Abstract Sauropod dinosaurs were the largest terrestrial
herbivores and pushed at the limits of vertebrate biomechanics
and physiology. Sauropods exhibit high craniodental
diversity in ecosystems where numerous species coexisted,
leading to the hypothesis that this biodiversity is
linked to niche subdivision driven by ecological specialisation.
Here, we quantitatively investigate feeding behaviour
hypotheses for the iconic sauropod Diplodocus. Biomechanical
modelling, using finite element analysis, was used to
examine the performance of the Diplodocus skull. Three
feeding behaviours were modelled: muscle-driven static biting,
branch stripping and bark stripping. The skull was found to be
‘over engineered’ for static biting, overall experiencing low
stress with only the dentition enduring high stress. When
branch stripping, the skull, similarly, is under low stress, with
little appreciable difference between those models. When simulated for bark stripping, the skull experiences far greater
stresses, especially in the teeth and at the jaw joint. Therefore,
we refute the bark-stripping hypothesis, while the hypotheses
of branch stripping and/or precision biting are both
consistent with our findings, showing that branch stripping
is a biomechanically plausible feeding behaviour
for diplodocids. Interestingly, in all simulations, peak
stress is observed in the premaxillary–maxillary ‘lateral
plates’, supporting the hypothesis that these structures
evolved to dissipate stress induced while feeding. These
results lead us to conclude that the aberrant craniodental
form of Diplodocus was adapted for food procurement
rather than resisting high bite forces.

Four juvenile specimens referable to Pinacosaurus grangeri (Ankylosauria: Dinosauria) are described from the Campanian (Upper Cretaceous) locality Bayan Mandahu in northern Inner Mongolia Autonomous Region (People’s Republic of China). All the specimens preserve the skulls as well as, in some cases, mandibles, postcrania, and osteoderm. They are not taphonomically deformed by expanding matrix distortion, unlike many Gobi specimens, including the holotype of P. grangeri. Bayan Mandahu is also the type locality for Pinacosaurus mephistocephalus. The proximity in space and time of these two closely related species warrants a generic and specific revision for Pinacosaurus. The distinction of the two species is based on characters of the squamosal dermal elaborations, cranial roof posterior to the orbits, premaxillary notch, and distal margin of the ilium. Although a relatively well-represented ankylosaur taxon, the phylogenetic position of Pinacosaurus has not been unequivocally resolved. A new analysis recovers Pinacosaurus as the most basal member of the Ankylosaurinae.

How theropod dinosaur skulls experience stress and strain during the application of adductor muscle loads provides a unique insight into their feeding behaviour and principles of skeletal construction and scaling. Of particular interest are unusual cranial morphologies, such as those seen in the spinosaurid theropods, Baryonyx walkeri, Suchomimus tenerensis, Irritator challengeri and Spinosaurus aegyptiacus. This study uses the engineering technique finite element analysis to reconstruct feeding-related stress and strain in the skulls of seven theropod dinosaurs: five non-neotetanurans (Afrovenator, Dubreuillosaurus, Monolophosaurus, Spinosaurus and Suchomimus) and two basal neotetanurans (Acrocanthosaurus, and Carcharodontosaurus). Two-dimensional finite element models are created, and simulated adductor muscle loads are applied in proportion to the lateral surface area of the skull, thereby removing the influence of size and testing the efficiency of shape at resisting relative loads. Results show a significant size-related trend, with large taxa experiencing greater stresses than smaller taxa. Whilst Suchomimus scales with other theropods, Spinosaurus is a notable outlier and experiences much higher magnitudes of cranial stress than would be predicted. It may be that when realistic loading parameters are considered, larger theropods mitigate potential cranial weakness through concomitnat scaling of adductor muscle and bite force or through modifications to feeding ecology, especially in taxa such as Spinosaurus. Give the 2D nature of these models, results and interpretations should be treated with caution, and are best considered predictors of biomechanical performance and feeding ecology, to be tested in the future with more appropriate 3D finite element models.

A nearly complete, well-preserved maxilla of an abelisaurid theropod from the early Late Cretaceous (middle Cenomanian-Turonian) Lower Member of the Bajo Barreal Formation of Chubut, Argentina represents the first definitive member of the abelisaurid clade from pre-Senonian (Coniacian–Maastrichtian) deposits. The new maxilla shares derived characters with the maxillae of Carnotaurus and Majungatholus, and with AMNH 1955, a maxilla previously referred to Indosuchus, suggesting that it pertains to the abelisaurid subclade Carnotaurinae. Abelisaurus shares apomorphic characters with Carnotaurinae, but many of these characters are also found in the carcharodontosaurid allosauroid Giganotosaurus. As it is known only from cranial material lacking carnotaurine synapomorphies, Abelisaurus may represent a late-surviving carcharodontosaurid derivative.
The presence of the Bajo Barreal predator in the early Late Cretaceous indicates that the origin of Abelisauridae had occurred by then. The occurrence of the new maxilla is nearly concurrent with the accepted interval of tectonic divergence between South America and Africa. Its discovery thus weakens support for the recent hypothesis that the abelisaurid clade could not have penetrated Africa. The known occurrence of Abelisauridae may reflect a former pan- Gondwanan distribution, and is thus of limited utility in the support of Late Cretaceous paleogeographic hypotheses.

Although diplodocoid sauropods from Africa and the Americas are well known, their European record remains largely neglected. Here we redescribe Dinheirosaurus lourinhanensis from the Late Jurassic of Portugal. The holotype comprises two posterior cervical vertebrae, the dorsal series and a caudal centrum. Redescription demonstrates its validity on the basis of three autapomorphies:(1) posteriorly restricted ventral keel on posterior cervical vertebrae;(2) three small subcircular fossae posterior to the lateral coel ...

Abstract:  The sauropod dinosaur, Barapasaurus tagorei, is known from the Early Jurassic Kota Formation (Sinemurian to Pliensbachian) of India. The taxon is represented by c. 300 bones that were found associated with large fossilized tree trunks and were collected from the interface of sandstone and mudstone units covering an area of c. 276 m2. The collection includes one partial skeleton; most of the remainder of the bones were disarticulated, disassociated and dispersed, but taphonomic analysis permits recognition of associated elements comprising several individuals. Skeletal anatomy of Barapasaurus includes several teeth, vertebrae from the caudal cervicals rearward to the terminal caudals, and most elements of the appendicular skeleton. Barapasaurus is characterized by spoon-shaped teeth with bulbous bases and grooves on the anterolabial and posterolingual sides of the crown, coarse tubercles on the carina, acamerate cranial and dorsal vertebrae, lateral laminae of the middle and caudal dorsal neural spines composed of spinodiapophyseal and spinopostzygapophyseal laminae, neural canal of the mid-dorsal vertebrae opens dorsally through a narrow slit into a large cavity and sacrum with four co-ossified vertebrae. Phylogenetic analysis reveals that Barapasaurus is basal in comparison with Vulcanodon and is removed from Eusauropoda.

Exceptionally complete, in ovo dinosaur embryos from the Upper Cretaceous of China are analysed. Ossification patterns of these embryos suggest that they died during the final third of their development. The therizinosauroid identity of the embryos follows from: (1) an edentulous premaxilla with a sharp downturned edge; (2) dentary with a lateral shelf; (3) teeth with fan-shaped crowns, with a few marginal cusps; (4) humerus with a massive deltopectoral crest extending proximally, with a pointed proximomedial tuberosity; (5) ilium with an expanded and hooked preacetabular process; (6) strongly curved hypertrophied manual unguals tapering to sharp points. These embryos are closest to two Chinese therizinosauroids, Neimongosaurus yangi Zhang et al. 2001 and Erliansaurus bellamanus Xu et al. 2002. An elongated narial opening, reduced basipterygoid process, low cervical neural spines, a transversely narrow pubic apron, and a pubic foot expanded anteriorly are found in these embryos and are synapomorphies uniting the Therizinosauroidea and the Oviraptorosauria. Fusion of cervical and caudal neural arches and centra, complete ossification of thoracic ribs and ilium, possible co-ossification of tibia and fibula, fused pubes, complete meta- and acropodial elements, together with small portions of unossified epiphyses of long bones suggest an advanced precociality of these embryos.

Background: Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species—Troodon formosus—presently known from substantial skeletal remains.

Methodology/Principal Findings: Here we report a gracile new troodontid theropod—Talos sampsoni gen. et sp. nov.— from the Upper Cretaceous Kaiparowits Formation, Utah, USA, representing one of the most complete troodontid skeletons described from North America to date. Histological assessment of the holotype specimen indicates that the adult body size of Talos was notably smaller than that of the contemporary genus Troodon. Phylogenetic analysis recovers Talos as a member of a derived, latest Cretaceous subclade, minimally containing Troodon, Saurornithoides, and Zanabazar. MicroCT scans reveal extreme pathological remodeling on pedal phalanx II-1 of the holotype specimen likely resulting from physical trauma and subsequent infectious processes.

Conclusion/Significance: Talos sampsoni adds to the singularity of the Kaiparowits Formation dinosaur fauna, which is represented by at least 10 previously unrecognized species including the recently named ceratopsids Utahceratops and Kosmoceratops, the hadrosaurine Gryposaurus monumentensis, the tyrannosaurid Teratophoneus, and the oviraptorosaurian Hagryphus. The presence of a distinct troodontid taxon in the Kaiparowits Formation supports the hypothesis that late Campanian dinosaurs of the Western Interior Basin exhibited restricted geographic ranges and suggests that the taxonomic diversity of Late Cretaceous troodontids from North America is currently underestimated. An apparent traumatic injury to the foot of Talos with evidence of subsequent healing sheds new light on the paleobiology of deinonychosaurians by bolstering functional interpretations of prey grappling and/or intraspecific combat for the second pedal digit, and supporting trackway evidence indicating a minimal role in weight bearing.

The ankylosaurs are one of the major dinosaur groups and are characterized by unique body armor. Previous studies on other dinosaur taxa have revealed growth patterns, life history and evolutionary mechanisms based on their long bone histology. However, to date nothing is known about long bone histology in the Ankylosauria. This study is the first description of ankylosaurian long bone histology based on several limb elements, which were sampled from different individuals from the Ankylosauridae and Nodosauridae. The histology is compared to that of other dinosaur groups, including other Thyreophora and Sauropodomorpha. Ankylosaur long bone histology is characterized by a fibrolamellar bone architecture. The bone matrix type in ankylosaurs is closest to that of Stegosaurus. A distinctive mixture of woven and parallel-fibered bone together with overall poor vascularization indicates slow growth rates compared to other dinosaurian taxa. Another peculiar characteristic of ankylosaur bone histology is the extensive remodeling in derived North American taxa. In contrast to other taxa, ankylosaurs substitute large amounts of their primary tissue early in ontogeny. This anomaly may be linked to the late ossification of the ankylosaurian body armor. Metabolically driven remodeling processes must have liberated calcium to ossify the protective osteodermal structures in juveniles to subadult stages, which led to further remodeling due to increased mechanical loading. Abundant structural fibers observed in the primary bone and even in remodeled bone may have improved the mechanical properties of the Haversian bone.

Biological Blood Pressure Limitations and More

Giant Sauropod Dinosaurs could not have eaten leaves from the tops of tall trees. 

The organic cellular structure of their hearts and blood vessels could not have created nor withstood the enormous blood pressure that would have been necessary to keep the brain alive and functioning vertically more than about nine feet above the heart.  Animal cell structures, either then or now, simply were incapable of being durable enough for the animals to survive.  Even today, giraffes cannot grow to be more than about 18 feet tall, and half of that is due to long legs.  A heart and circulatory system made of known biological cellular tissues cannot create blood pressure sufficient to pump blood more than about nine vertical feet above the heart, or bring blood back from legs and feet lower than about nine feet below it.  Giraffes even have to have unique "braided" blood paths in their necks to and from the head, to reduce the danger of cerebral strokes if the head is quickly raised or lowered, to avoid bursting tiny capillaries in their brains and to minimize heart valve failures and blood vessels bursting.  Male giraffes are around seventeen feet tall, with their heart about at eight or nine feet high.  Giraffe hearts and circulatory systems are as sturdy as has ever been known in animals.

A number of commonly accepted assumptions about large dinosaurs are not compatible with scientific laws.  For example, sauropods grazing from the tops of trees were physiologically impossible, for blood flow reasons.  If any part of any dinosaur’s body ever got above eighteen feet high, blood flow would cease and cell death would be imminent.  If this included the brain, lack of consciousness would quickly occur.  If this resulted in a fall, a blood pressure surge would occur in the brain, with a likely fatal stroke.  Since large dinosaurs seem to have lived for hundreds of years, and they existed for many millions of years, we have to believe that this rarely happened.

I first discovered this logic around 1996, and published this result.  By around 1998, many of the major Museums around the world recognized this and they disassembled their "high-reaching Sauropod" displays to reassemble them with their heads and necks cantilevered horizontally in front of them.

Recent biomechanical evidence has fuelled debate surrounding the winter habits of the hadrosaurian dinosaur Edmontosaurus (ca. 70 Ma). Using histological characteristics recorded in bone, we show that polar Edmontosaurus endured the long winter night. In contrast, the bone microstructure of temperate Edmontosaurus is inconsistent with a perennially harsh environment. Differences in the bone microstructure of polar and temperate Edmontosaurus consequently dispute the hypothesis that polar populations were migratory. The overwintering signal preserved in the microstructure of polar Edmontosaurus bone offers significant insight into the life history of dinosaurs within the Late Cretaceous Arctic.

ABSTRACT Jurassic sandstones of the Hartford Basin are well known for their dinosaur trackways, but few studies have characterized their invertebrate ichnofaunas. A notable Portland Formation exposure in this area is the Hoover Quarry in East Longmeadow, Massachusetts, where vertebrate skeletal material (the type specimen of the crocodilian Stegomosuchus longipes) occurs in association with a diverse ichnofauna. Hoover Quarry ichnogenera include Eubrontes cf.

New material of the rare ankylosaurid dinosaur Nodocephalosaurus kirtlandensis Sullivan, 1999 is identified and described. Specimens include cephalic osteoderms, a cervical spine, and two caudal vertebrae. The caudal vertebrae are distinct from other known North American ankylosaurids (such as Euoplocephalus tutus), thus reinforcing their taxonomic assignment to N. kirtlandensis. Presently, N. kirtlandensis is known only from the De-na-zin Member of the Kirtland Formation, San Juan Basin, New Mexico.