scholarly journals FANTASY VS REALITY: A Critique of Smith et al.'s Bird Origins

2016 ◽  
Vol 9 (1) ◽  
pp. 14-38 ◽  
Author(s):  
Alan Feduccia
Keyword(s):  
Late Cretaceous ◽  
Theropod Dinosaurs ◽  
Terrestrial Predator ◽  
Bird Origins

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.

Parataxonomic classification of ornithoid eggshell fragments from the Oldman Formation (Judith River Group; Upper Cretaceous), southern Alberta

1996 ◽  
Vol 33 (12) ◽  
pp. 1655-1667 ◽  
Author(s):  
Darla K. Zelenitsky ◽  
L. V. Hills ◽  
Philip J. Currie
Keyword(s):  
Late Cretaceous ◽  
Shell Thickness ◽  
Upper Cretaceous ◽  
Theropod Dinosaur ◽  
Surface Sculpture ◽  
External Zone ◽  
Theropod Dinosaurs ◽  
Southern Alberta ◽  
The Family

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.

scholarly journals Comparative digestive physiology of archosaurs with notes on bird origins

2018 ◽  
Author(s):  
Piotr Bajdek
Keyword(s):  
Gut Contents ◽  
Metabolic Rates ◽  
Digestive Physiology ◽  
Digestion Time ◽  
Theropod Dinosaurs ◽  
The Difference ◽  
Phylogenetic Hypotheses ◽  
Bird Origins

It is widely accepted that birds evolved from theropod dinosaurs, and few paleontologists disagree preferring a more ancient split of the avian and dinosaur lineages. The difference in digestive physiology between members of the theropod and crocodile lineages, documented by fossil feces and gut contents, offers an opportunity to test these phylogenetic hypotheses. Birds share with crocodiles the functional gizzard that contains swallowed stones and where gastric pellets are formed before regurgitation, as well as a mechanism that prevents the passage of indigestible residues into the intestine. Both these adaptations are missing in unquestionable theropod groups (compsognathids, tyrannosaurids, allosaurids, coelophysids). The theropod ancestry of birds implies reappearance and strong development of a specific stomach functionality that either had been already lost in the theropod dinosaurs or was never present in their lineage. Coprolites of early archosaurs contain undigested bones, which suggests a short digestion time and higher metabolic rates than in extant crocodiles. Early archosaurs were similar to birds, but not to dinosaurs, in all these aspects of physiology.

scholarly journals Comparative digestive physiology of archosaurs with notes on bird origins

2018 ◽  
Author(s):  
Piotr Bajdek
Keyword(s):  
Gut Contents ◽  
Metabolic Rates ◽  
Digestive Physiology ◽  
Digestion Time ◽  
Theropod Dinosaurs ◽  
The Difference ◽  
Phylogenetic Hypotheses ◽  
Bird Origins

It is widely accepted that birds evolved from theropod dinosaurs, and few paleontologists disagree preferring a more ancient split of the avian and dinosaur lineages. The difference in digestive physiology between members of the theropod and crocodile lineages, documented by fossil feces and gut contents, offers an opportunity to test these phylogenetic hypotheses. Birds share with crocodiles the functional gizzard that contains swallowed stones and where gastric pellets are formed before regurgitation, as well as a mechanism that prevents the passage of indigestible residues into the intestine. Both these adaptations are missing in unquestionable theropod groups (compsognathids, tyrannosaurids, allosaurids, coelophysids). The theropod ancestry of birds implies reappearance and strong development of a specific stomach functionality that either had been already lost in the theropod dinosaurs or was never present in their lineage. Coprolites of early archosaurs contain undigested bones, which suggests a short digestion time and higher metabolic rates than in extant crocodiles. Early archosaurs were similar to birds, but not to dinosaurs, in all these aspects of physiology.

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 ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Theropod Dinosaurs

scholarly journals Dinosaur origin of egg color: oviraptors laid blue-green eggs

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3706 ◽  
Author(s):  
Jasmina Wiemann ◽  
Tzu-Ruei Yang ◽  
Philipp N. Sander ◽  
Marion Schneider ◽  
Marianne Engeser ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Paternal Care ◽  
First Record ◽  
Nesting Behavior ◽  
Theropod Dinosaurs ◽  
Cryptic Coloration ◽  
Stage Embryo ◽  
Late Developmental Stage ◽  
Signaling Hypothesis ◽  
Egg Coloration

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.

Early Mesozoic Terrestrial Ecosystems: Faunal Changes Among Vertebrates

2000 ◽  
Vol 6 ◽  
pp. 115-140 ◽  
Author(s):  
Nicholas C. Fraser
Keyword(s):  
Morphological Characteristics ◽  
Terrestrial Ecosystems ◽  
The Past ◽  
Theropod Dinosaurs ◽  
Highly Active ◽  
The Face ◽  
Alternative Hypotheses ◽  
The Subject ◽  
Triassic Period ◽  
Bird Origins

The past decade has seen many advances in research on vertebrate faunas of the Triassic period. The end of the Triassic now is cited widely as the dawn of modern terrestrial ecosystems, and currently the earliest mammals, turtles, lissamphibians (frogs, toads and salamanders), lizards, and crocodiles are all documented from this period. Admittedly many of these early members of present day higher order taxa were very different from their modern counterparts. For instance, the earliest crocodiles were highly active cursorial forms (e.g., Crush, 1984), and the mammals were very different to the living placentals and marsupials. Nevertheless, they possessed many of the key morphological characteristics that diagnose the group and that may well have contributed to their ultimate success. However, the Triassic was also a time of bizarre and enigmatic tetrapods, some of whose relationships are the subject of considerable debate. Indeed, in the last year this debate has reached new heights with suggestions that certain rather unusual Triassic non-dinosaurian tetrapods may have more bearing on bird origins than theropod dinosaurs. This debate has been fueled by the discoveries of feathered dinosaurs from China which, on the face of it, one might expect to dampen the search for alternative hypotheses regarding bird origins.

Enigmatic teeth of small theropod dinosaurs from the Upper Cretaceous (Cenomanian–Turonian) of Uzbekistan

2013 ◽  
Vol 50 (3) ◽  
pp. 306-314 ◽  
Author(s):  
Hans-Dieter Sues ◽  
Alexander Averianov
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Theropod Dinosaurs ◽  
Kyzylkum Desert

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.

scholarly journals Comparative digestive physiology of archosaurs with notes on bird origins

2018 ◽  
Author(s):  
Piotr Bajdek
Keyword(s):  
Gut Contents ◽  
Metabolic Rates ◽  
Digestive Physiology ◽  
Digestion Time ◽  
Theropod Dinosaurs ◽  
The Difference ◽  
Phylogenetic Hypotheses ◽  
Bird Origins

It is widely accepted that birds evolved from theropod dinosaurs, and few paleontologists disagree preferring a more ancient split of the avian and dinosaur lineages. The difference in digestive physiology between members of the theropod and crocodile lineages, documented by fossil feces and gut contents, offers an opportunity to test these phylogenetic hypotheses. Birds share with crocodiles the functional gizzard that contains swallowed stones and where gastric pellets are formed before regurgitation, as well as a mechanism that prevents the passage of indigestible residues into the intestine. Both these adaptations are missing in unquestionable theropod groups (compsognathids, tyrannosaurids, allosaurids, coelophysids). The theropod ancestry of birds implies reappearance and strong development of a specific stomach functionality that either had been already lost in the theropod dinosaurs or was never present in their lineage. Coprolites of early archosaurs contain undigested bones, which suggests a short digestion time and higher metabolic rates than in extant crocodiles. Early archosaurs were similar to birds, but not to dinosaurs, in all these aspects of physiology.

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