Hadrosaurs Research Papers - Academia.edu (original) (raw)
My first "scientific" paper, LOL. Several other firsts here- this is the first description of a dinosaur bone from the Edmonton, Alberta area (though one paper previously misidentified a hadrosaur vertebra as plesiosaur); best 6-view... more
My first "scientific" paper, LOL. Several other firsts here- this is the first description of a dinosaur bone from the Edmonton, Alberta area (though one paper previously misidentified a hadrosaur vertebra as plesiosaur); best 6-view drawings of a hadrosaur femur, and first published drawings done by Tyrrell scientific illustrator Donna L. Sloan whose work has frequently appeared in many scientific papers by Philip J. Currie, Betsy Nicholls, Don Brinkman and others.
Впервые описанный 70 лет назад гадрозаврид Orthomerus weberi основан преимущественно на костях нижнего отдела задней лапы из маастрихта (верхний мел) Крымского полуострова, Россия. Отсутствие костей черепа, таза и позвоночного столба... more
Впервые описанный 70 лет назад гадрозаврид Orthomerus weberi основан преимущественно на
костях нижнего отдела задней лапы из маастрихта (верхний мел) Крымского полуострова,
Россия. Отсутствие костей черепа, таза и позвоночного столба сильно усложняют
диагностирование Orthomerus weberi , однако, новые данные о утконосых динозаврах,
накопленные за эти десятилетия, а также сравнение крымских останков с другими
представителями Hadrosauria, показывают комбинацию уникальных признаков, позволяющих
создать для данного вида свой отдельный род Riabininohadros gen. nov.
Jaw mechanics in ornithischian dinosaurs have been widely studied for well over a century. Most of these studies, however, use only one or few taxa within a given ornithischian clade as a model for feeding mechanics across the entire... more
Jaw mechanics in ornithischian dinosaurs have been widely studied for well over a century. Most of these studies, however, use only one or few taxa within a given ornithischian clade as a model for feeding mechanics across the entire clade. In this study, mandibular mechanical advantages among 52 ornithischian genera spanning all subclades are calculated using 2D lever arm methods. These lever arm calculations estimate the effect of jaw shape and difference in adductor muscle line of action on relative bite forces along the jaw. Results show major instances of overlap between taxa in tooth positions at which there was highest mechanical advantage. A relatively low bite force is seen across the tooth row among thyreophorans (e.g., stegosaurs and ankylosaurs), with variation among taxa. A convergent transition occurs from a more evenly distributed bite force along the jaw in basal ornithopods and basal marginocephalians to a strong distal bite force in hadrosaurids and cera-topsids, respectively. Accordingly, adductor muscle vector angles show repeated trends from a mid-range caudodorsal orientation in basal orni-thischians to a decrease in vector angles indicating more caudally oriented jaw movements in derived taxa (e.g., derived thyreophorans, basal ornithopods, lambeosaurines, pachycephalosaurs, and derived ceratop-sids). Analyses of hypothetical jaw morphologies were also performed, indicating that both the coronoid process and lowered jaw joint increase moment arm length therefore increasing mechanical advantage of the jaw apparatus. Adaptive trends in craniomandibular anatomy show that orni-thischians evolved more complex feeding apparatuses within different clades as well as morphological convergences between clades. Anat Rec, 299:271–294, 2016. V C 2015 Wiley Periodicals, Inc.
ABSTRACT This study describes a hadrosaurid braincase that has preserved a natural brain endocast, which was found at a locality in the Cerro del Pueblo Formation, Coahuila, Mexico. The braincase is extremely well preserved and includes... more
ABSTRACT This study describes a hadrosaurid braincase that has preserved a natural brain endocast, which was found at a locality in the Cerro del Pueblo Formation, Coahuila, Mexico. The braincase is extremely well preserved and includes almost all bone elements that surrounded the brain. The brain endocast includes all the cerebral regions and cranial nerves. This specimen is similar in shape to the brain described for Gryposaurus notabilis.
The Arabian fossil potential had been largely unexplored until the last two decades. Although its fossil record has improved considerably in terms of quantity, it still largely consists of poorly preserved undiagnostic material. Here we... more
The Arabian fossil potential had been largely unexplored until the last two decades. Although its fossil record has improved considerably in terms of quantity, it still largely consists of poorly preserved undiagnostic material. Here we describe a newly discovered enigmatic ornithopod braincase from the Al-Khod Conglomerate Formation of Oman. This formation fills an important spatio-temporal gap, given its position in between Africa and Eurasia, its long palaeogeographic relationship with Africa and being latest Cretaceous (post-Cenomanian) in age. It has produced one of the most taxonomically diverse latest Cretaceous faunas for any Gondwanan landmass and a significant portion of all dinosaur records from the Arabian Peninsula. The braincase is assigned to Ornithopoda on the basis of: a U-shaped occipital condyle, the dorsoventral proportions of the posterior braincase and the angle of the exoccipital-supraoccipital contact. Unlike typical ornithopods it displays short and laterally restricted basipterygoids, prominent basal tuberi and a narrow dorsal skull margin. Endocranial features including a very narrow and steep median ridge, the inner ear morphology and the hypoglossal arrangement are more typical of ornithopods. A unique combination of features, most notably: the separate canal for the ophthalmic branch of the trigeminal nerve (CN V), the large fossa above the cerebral carotid foramen, and an almost total absence of a floccular recess, justify an identification as a non-hadrosaurid ornithopod. The presence of various (generally small-sized) ornithopod lineages combined with peculiar morphologies in the Al-Khod vertebrate fauna paradoxically hints at periodic isolation and potentially trans-Tethys faunal connectivity between Afro-Arabia and Eurasia.
In this chapter we describe the pioneering exploration of Upper Cretaceous dinosaur localities in the Amur Region by Russian scientists, ranging from the Great Siberian Expedition at the end of the 1850s, until the discovery, in 1948, of... more
In this chapter we describe the pioneering exploration of Upper Cretaceous dinosaur localities in the Amur Region by Russian scientists, ranging from the Great Siberian Expedition at the end of the 1850s, until the discovery, in 1948, of the Blagoveschensk bonebed. As a complement to the anatomical description of the lambeosaurine hadrosaur, Amurosaurus riabinini, several interesting bones discovered during more recent excavations of the Blagoveschensk bonebed are described. Amurosaurus rarely reached skeletal maturity and the largest humerus unearthed from the Blagoveschensk bonebed corresponds to an animal about 9 m long for an estimated weight of about 4000 kg. The long, caudally open external naris and the shallowly concave dorsal profile of the premaxilla in a presumed sexually mature specimen are consistent with the basal position of Amurosaurus in the phylogeny of lambeosaurines. Accordingly, it is possible that the nasal passage was not completely enclosed by the premaxilla in adults, as is the case for North American adult lambeosaurines, and instead was partially covered by a skin membrane. The low neural spines of the sacrals are a potential autapomorphic character of Amurosaurus riabinini.
During the latest Cretaceous, the European Archipelago was characterized by highly fragmented landmasses hosting putative dwarfed, insular dinosaurs, claimed as fossil evidence of the “island rule”. The Villaggio del Pescatore quarry... more
During the latest Cretaceous, the European Archipelago was characterized by highly fragmented landmasses hosting putative dwarfed, insular dinosaurs, claimed as fossil evidence of the “island rule”. The Villaggio del Pescatore quarry (north-eastern Italy) stands as the most informative locality within the palaeo-Mediterranean region and represents the first, multi-individual Konservat-Lagerstätte type dinosaur-bearing locality in Italy. The site is here critically re-evaluated as early Campanian in age, thus preceding the final fragmentation stages of the European Archipelago, including all other European localities preserving hypothesized dwarfed taxa. New skeletal remains allowed osteohistological analyses on the hadrosauroid Tethyshadros insularis indicating subadult features in the type specimen whereas a second, herein newly described, larger individual is likely somatically mature. A phylogenetic comparative framework places the body-size of T. insularis in range with other non-hadrosaurid Eurasian hadrosauroids, rejecting any significant evolutionary trend towards miniaturisation in this clade, confuting its ‘pygmy’ status, and providing unmatched data to infer environmentally-driven body-size trends in Mesozoic dinosaurs.
The eastern Tremp Syncline (northeastern Spain) is the richest European locality for latest Cretaceous hadrosauroids. We summarize the record of hadrosauroid skeletal remains from 33 localities and tracks from 15 sites in the Tremp... more
The eastern Tremp Syncline (northeastern Spain) is
the richest European locality for latest Cretaceous hadrosauroids.
We summarize the record of hadrosauroid skeletal
remains from 33 localities and tracks from 15 sites in the
Tremp Formation. Two of the bone-bearing localities occur
in the Early/Late Maastrichtian “gray unit,” whereas all
other sites occur in the Late Maastrichtian “lower red unit.”
The skeletal sample represents more than 1,000 elements,
mostly axial and appendicular, although several mandibular
and skull bones have been recovered. The eastern Tremp
Syncline includes the hitherto only known hadrosauroid
bonebed from Europe, as well as the “tsintaosaur” lambeosaurine
Pararhabdodon isonensis. Hadrosauroids are less
abundant than sauropods in the gray unit, whereas they are
much more abundant in the overlying lower red unit where
sauropod bones are rare. This turnover is best explained as
a time/event-related faunal change at the beginning of the
Late Maastrichtian. The apparent absence of hadrosauroid
eggshells and hatchlings suggests that the nesting grounds of
these animals occurred far from the depositional areas of the
Tremp Syncline, thus remaining unrecorded unlike the egg
remains of coeval sauropods. The skeletal sample is mostly
composed of individuals much smaller than those regarded
as adults for the hadrosaurid taxa of the latest Cretaceous of
western North America and Asia, although a few larger individuals
in the adult size range exist. This may be explained
by the prevalence of juvenile individuals compared to adults,
the presence of both small and large-sized species in the
sample, or by the occasional presence of unusually large
individuals within populations of relatively moderate body
size, and possibly dwarfs.