scholarly journals A new specimen of Shuvuuia deserti Chiappe et al., 1998, from the Mongolian Late Cretaceous with a discussion of the relationships of alvarezsaurids to other theropod dinosaurs

2002 ◽  
Vol 494 ◽  
pp. 1-18
Author(s):  
Shigeru Suzuki ◽  
Luis M. Chiappe ◽  
Gareth Dyke ◽  
Mahito Watabe ◽  
R. Barsbold ◽  
...  
1996 ◽  
Vol 33 (12) ◽  
pp. 1655-1667 ◽  
Author(s):  
Darla K. Zelenitsky ◽  
L. V. Hills ◽  
Philip J. Currie

Examination of a large number of eggshell fragments collected from the Oldman Formation of southern Alberta reveals a greater ootaxonomic diversity than is known from complete eggs or clutches. Three new oogenera and oospecies of the ornithoid-ratite morphotype and one of the ornithoid-prismatic morphotype are established, based on the eggshell fragments. Porituberoolithus warnerensis oogen. et oosp. nov. and Continuoolithus canadensis oogen. et oosp. nov. have a microstructure similar to that of elongatoolithid eggs of theropod dinosaurs. Tristraguloolithus cracioides oogen. et oosp. nov. and Dispersituberoolithus exilis oogen. et oosp. nov. possess an external zone and thus have a microstructure like modern avian eggshell. Tristraguloolithus has a shell thickness, microstructure, and surface sculpture similar to those of recent bird eggshell of the family Cracidae (order Galliformes). Dispersituberoolithus exhibits the primitive or normal eggshell condition of some recent neognathous avian taxa. The ootaxa described indicate a diversity of both avian and theropod dinosaur egg layers within Devil's Coulee and Knight's Ranch, southern Alberta, during the Late Cretaceous.


PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3706 ◽  
Author(s):  
Jasmina Wiemann ◽  
Tzu-Ruei Yang ◽  
Philipp N. Sander ◽  
Marion Schneider ◽  
Marianne Engeser ◽  
...  

Protoporphyrin (PP) and biliverdin (BV) give rise to the enormous diversity in avian egg coloration. Egg color serves several ecological purposes, including post-mating signaling and camouflage. Egg camouflage represents a major character of open-nesting birds which accomplish protection of their unhatched offspring against visually oriented predators by cryptic egg coloration. Cryptic coloration evolved to match the predominant shades of color found in the nesting environment. Such a selection pressure for the evolution of colored or cryptic eggs should be present in all open nesting birds and relatives. Many birds are open-nesting, but protect their eggs by continuous brooding, and thus exhibit no or minimal eggshell pigmentation. Their closest extant relatives, crocodiles, protect their eggs by burial and have unpigmented eggs. This phylogenetic pattern led to the assumption that colored eggs evolved within crown birds. The mosaic evolution of supposedly avian traits in non-avian theropod dinosaurs, however, such as the supposed evolution of partially open nesting behavior in oviraptorids, argues against this long-established theory. Using a double-checking liquid chromatography ESI-Q-TOF mass spectrometry routine, we traced the origin of colored eggs to their non-avian dinosaur ancestors by providing the first record of the avian eggshell pigments protoporphyrin and biliverdin in the eggshells of Late Cretaceous oviraptorid dinosaurs. The eggshell parataxonMacroolithus yaotunensiscan be assigned to the oviraptorHeyuannia huangibased on exceptionally preserved, late developmental stage embryo remains. The analyzed eggshells are from three Late Cretaceous fluvial deposits ranging from eastern to southernmost China. Reevaluation of these taphonomic settings, and a consideration of patterns in the porosity of completely preserved eggs support an at least partially open nesting behavior for oviraptorosaurs. Such a nest arrangement corresponds with our reconstruction of blue-green eggs for oviraptors. According to the sexual signaling hypothesis, the reconstructed blue-green eggs support the origin of previously hypothesized avian paternal care in oviraptorid dinosaurs. Preserved dinosaur egg color not only pushes the current limits of the vertebrate molecular and associated soft tissue fossil record, but also provides a perspective on the potential application of this unexplored paleontological resource.


2013 ◽  
Vol 50 (3) ◽  
pp. 306-314 ◽  
Author(s):  
Hans-Dieter Sues ◽  
Alexander Averianov

Upper Cretaceous (Cenomanian–Turonian) formations in the Kyzylkum Desert of Uzbekistan, especially the Bissekty Formation at Dzharakuduk, have yielded a great diversity of continental vertebrates, including dinosaurs. Underwater screening of the sandy matrix has recovered many dinosaurian teeth. Here we describe and illustrate two types of enigmatic theropod teeth that are referable to Paronychodon and Richardoestesia, respectively. Both of these tooth taxa are well known from the Late Cretaceous of North America and possibly represent stages in the development of the teeth of various paravian theropods. Confirmation of this hypothesis awaits discovery of more complete jaws.


2016 ◽  
Vol 9 (1) ◽  
pp. 14-38 ◽  
Author(s):  
Alan Feduccia

Adherents of the current orthodoxy of a derivation of birds from theropod dinosaurs, criticize the commentary by Feduccia (2013, Auk, 130) [1 - 12] entitled “Bird Origins Anew” as well as numerous papers by Lingham-Soliar on theropod dermal fibers, using numerous mischaracterizations and misstatements of content, and illustrate their own misconceptions of the nature of the debate, which are here clarified. While there is general agreement with the affinity of birds and maniraptorans, the widely accepted phylogeny, advocating derived earth-bound maniraptorans giving rise to more primitive avians (i.e. Archaeopteryx), may be “topsy-turvy.” The current primary debate concerns whether maniraptorans are ancestral or derived within the phylogeny, and whether many maniraptorans and birds form a clade distinct from true theropods. Corollaries of the current scheme show largely terrestrial maniraptoran theropods similar to the Late CretaceousVelociraptorgiving rise to avians, and flight originatingviaa terrestrial (cursorial) “gravity-resisted,” as opposed to an arboreal “gravity-assisted” model. The current dogma posits pennaceous flight remiges in earth-bound theropods having evolved in terrestrial theropods that never flew. As part of the orthodoxy, fully feathered maniraptorans such as the tetrapteryx glidersMicroraptorand allies, are incorrectly reconstructed as terrestrial cursors, when in reality their anatomy and elongate hindlimb feathers would be a hindrance to terrestrial locomotion.The same is true of many early birds, exemplified by reconstruction of the arboreally adaptedConfuciusornisas a terrestrial predator, part of the overall theropodan scheme of birds evolving from terrestrial dinosaurs, and flight from the ground up. Both sides of this contentious debate must be constantly aware that new fossil or even molecular discoveries on birds may change current conclusions.


2019 ◽  
Author(s):  
Felipe C. Montefeltro ◽  
Stephan Lautenschlager ◽  
Pedro L. Godoy ◽  
Gabriel S. Ferreira ◽  
Richard J. Butler

ABSTRACTTheropod dinosaurs were relatively scarce in the Late Cretaceous ecosystems of southeast Brazil. Instead, hypercarnivorous crocodyliforms known as baurusuchids were abundant and probably occupied the ecological role of apex predators. Baurusuchids exhibited a series of morphological adaptations hypothesised to be associated with this ecological role, but quantitative biomechanical analyses of their morphology have so far been lacking. Here, we employ a biomechanical modelling approach, applying finite element analysis (FEA) to models of the skull and mandibles of a baurusuchid specimen. This allowed us to characterise the craniomandibular apparatus of baurusuchids, as well as to compare the functional morphology of the group to that of other archosaurian carnivores, such as theropods and crocodylians. Our results support the ecological role of baurusuchids as specialised apex predators in the continental Late Cretaceous ecosystems of South America. With a relatively weak bite force (∼600 N), baurusuchids’ predation strategies likely relied on other morphological specializations, such as ziphodont dentition and strong cervical musculature. Comparative assessments of the stress distribution and magnitude of scaled models of other predators (the theropod Allosaurus fragilis and the living crocodylian Alligator mississippiensis) consistently show different responses to loadings under the same functional scenarios, suggesting distinct predatory behaviours for these animals. The unique selective pressures in the arid to semi-arid Late Cretaceous ecosystems of southeast Brazil, which were dominated by crocodyliforms, possibly drove the emergence and evolution of the biomechanical features seen in baurusuchids, which are distinct from those previously reported for other predatory taxa.


2021 ◽  
Vol 24 (4) ◽  
pp. 387-396
Author(s):  
Carlos Roberto Candeiro ◽  
Stephen Brusatte ◽  
Glayce Queiroz ◽  
Adelino Carvalho ◽  
Débora Maia ◽  
...  

The southern Goiás state region of Central Brazil has an extensive and informative record of fossil biota. Particularly over the last five years, there has been a great increase in fossil finds, which has enabled a greater understanding of this region's fauna and flora during the Late Cretaceous. In this article, we provide an updated synthesis of the biota from the Cretaceous of the southern Goiás state, the record of plants, gastropods, turtles, crocodilians, titanosaurs, and theropod dinosaurs.


2021 ◽  
Author(s):  
Tibor Pecsics

ABSTRACT The first trace fossils in Hungary, dinosaur footprints, were found in the coal mines of the Mecsek Mountains. The footprints belonged to small theropod dinosaurs. The first fossil bones of vertebrate animals from present-day Hungary were found in 2000 in the mountainous region of Bakony. Numerous taxa have been collected from the locality of Iharkút. These fossils represent a diverse fauna (including fishes, amphibians, turtles, lizards, crocodilians, dinosaurs, birds, and pterosaurs) that lived between 85.8 and 83.5 m.y. ago in the Santonian Age during the Late Cretaceous period. Paleoart can depict these fossil remains in an engaging way to help inform the public about the ancient creatures of Hungary. This chapter provides an overview of how the Mesozoic vertebrates from Hungary have been reconstructed for scientists and the public.


2019 ◽  
Vol 47 (1) ◽  
pp. 519-553 ◽  
Author(s):  
David W. Krause ◽  
Joseph J.W. Sertich ◽  
Patrick M. O'Connor ◽  
Kristina Curry Rogers ◽  
Raymond R. Rogers

The Mesozoic plate tectonic and paleogeographic history of Gondwana had a profound effect on the distribution of terrestrial vertebrates. As the supercontinent fragmented into a series of large landmasses (South America, Africa-Arabia, Antarctica, Australia, New Zealand, the Indian subcontinent, and Madagascar), particularly during the Late Jurassic and Cretaceous, its terrestrial vertebrates became progressively isolated, evolving into unique faunal assemblages. We focus on four clades that, during the Mesozoic, had relatively low ability for dispersal across oceanic barriers—crocodyliforms, sauropod dinosaurs, nonavian theropod dinosaurs, and mammals. Their distributions reveal patterns that are critically important in evaluating various biogeographic hypotheses, several of which have been informed by recent discoveries from the Late Cretaceous of Madagascar. We also examine the effects of lingering, intermittent connections, or reconnections, of Gondwanan landmasses with Laurasia (through the Caribbean, Mediterranean, and Himalayan regions) on the distributions of different clades. ▪ This article reviews the biogeographic history of terrestrial vertebrates from the Mesozoic of the southern supercontinent Gondwana. ▪ Relatively large, terrestrial animals—including crocodyliforms, sauropod and nonavian theropod dinosaurs, and mammals—are the focus of this review. ▪ Most patterns related to vicariance occurred during the Late Jurassic and Cretaceous, the intervals of most active Gondwanan fragmentation. ▪ Recent discoveries of vertebrates from the Late Cretaceous of Madagascar have played a key role in formulating and testing various biogeographic hypotheses.


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