Topic
Deinonychus
About: Deinonychus is a research topic. Over the lifetime, 21 publications have been published within this topic receiving 1119 citations. The topic is also known as: Deinonychus & Velociraptor antirrhopus.
Papers
TL;DR: There is no evidence for a major or mass extinction of birds at the end of the Cretaceous, nor for a sudden ‘bottleneck’ in diversity that fostered the early Tertiary origination of living bird ‘Orders’.
Abstract: Birds evolved from and are phylogenetically recognized as members of the theropod dinosaurs; their first known member is the Late Jurassic Archaeopteryx, now represented by seven skeletons and a feather, and their closest known non-avian relatives are the dromaeosaurid theropods such as Deinonychus. Bird flight is widely thought to have evolved from the trees down, but Archaeopteryx and its outgroups show no obvious arboreal or tree-climbing characters, and its wing planform and wing loading do not resemble those of gliders. The ancestors of birds were bipedal, terrestrial, agile, cursorial and carnivorous or omnivorous. Apart from a perching foot and some skeletal fusions, a great many characters that are usually considered ‘avian’ (e.g. the furcula, the elongated forearm, the laterally flexing wrist and apparently feathers) evolved in non-avian theropods for reasons unrelated to birds or to flight. Soon after Archaeopteryx, avian features such as the pygostyle, fusion of the carpometacarpus, and elongated curved pedal claws with a reversed, fully descended and opposable hallux, indicate improved flying ability and arboreal habits. In the further evolution of birds, characters related to the flight apparatus phylogenetically preceded those related to the rest of the skeleton and skull. Mesozoic birds are more diverse and numerous than thought previously and the most diverse known group of Cretaceous birds, the Enantiornithes, was not even recognized until 1981. The vast majority of Mesozoic bird groups have no Tertiary records: Enantiornithes, Hesperornithiformes, Ichthyornithiformes and several other lineages disappeared by the end of the Cretaceous. By that time, a few Linnean ‘Orders’ of extant birds had appeared, but none of these taxa belongs to extant ‘families’, and it is not until the Paleocene or (in most cases) the Eocene that the majority of extant bird ‘Orders’ are known in the fossil record. There is no evidence for a major or mass extinction of birds at the end of the Cretaceous, nor for a sudden ‘bottleneck’ in diversity that fostered the early Tertiary origination of living bird ‘Orders’.
397 citations
TL;DR: “stability flapping” is described, a novel behaviour executed for positioning and stability during the initial stages of prey immobilisation, which may have been pivotal to the evolution of the flapping stroke.
Abstract: Most non-avian theropod dinosaurs are characterized by fearsome serrated teeth and sharp recurved claws. Interpretation of theropod predatory ecology is typically based on functional morphological analysis of these and other physical features. The notorious hypertrophied ‘killing claw’ on pedal digit (D) II of the maniraptoran theropod Deinonychus (Paraves: Dromaeosauridae) is hypothesized to have been a predatory adaptation for slashing or climbing, leading to the suggestion that Deinonychus and other dromaeosaurids were cursorial predators specialized for actively attacking and killing prey several times larger than themselves. However, this hypothesis is problematic as extant animals that possess similarly hypertrophied claws do not use them to slash or climb up prey. Here we offer an alternative interpretation: that the hypertrophied D-II claw of dromaeosaurids was functionally analogous to the enlarged talon also found on D-II of extant Accipitridae (hawks and eagles; one family of the birds commonly known as “raptors”). Here, the talon is used to maintain grip on prey of subequal body size to the predator, while the victim is pinned down by the body weight of the raptor and dismembered by the beak. The foot of Deinonychus exhibits morphology consistent with a grasping function, supportive of the prey immobilisation behavior model. Opposite morphological trends within Deinonychosauria (Dromaeosauridae + Troodontidae) are indicative of ecological separation. Placed in context of avian evolution, the grasping foot of Deinonychus and other terrestrial predatory paravians is hypothesized to have been an exaptation for the grasping foot of arboreal perching birds. Here we also describe “stability flapping”, a novel behaviour executed for positioning and stability during the initial stages of prey immobilisation, which may have been pivotal to the evolution of the flapping stroke. These findings overhaul our perception of predatory dinosaurs and highlight the role of exaptation in the evolution of novel structures and behaviours.
116 citations
TL;DR: A unique find of a partial egg in contact with articulated gastralia from a known specimen of the dromaeosaurid Deinonychus antirrhopus (AMNH 3015) is described in this article.
Abstract: A unique find of a partial egg in contact with articulated gastralia from a known specimen of the dromaeosaurid Deinonychus antirrhopus (AMNH 3015) is described. Much of the original taphonomic con...
74 citations
74 citations
TL;DR: The hypothesis of mammal-like cooperative pack hunting in D. antirrhopus and other nonavian theropods is assessed by examining the behaviors of extant diapsids and it is concluded that this hypothesis is both unparsimonious and unlikely for these taxa and that the null hypothesis should therefore be that nonavIAN theropod dinosaurs were solitary hunters or, at most, foraged in loose associations.
Abstract: Since the 1969 description of Deinonychus antirrhopus Ostrom, cooperative pack hunting behavior for this species and, subsequently, for many other nonavian theropods, has attained wide acceptance. In this paper we assess the hypothesis of mammal-like cooperative pack hunting in D. antirrhopus and other nonavian theropods by examining the behaviors of extant diapsids. Through phylogenetic inference and character optimization, we conclude that this hypothesis is both unparsimonious and unlikely for these taxa and that the null hypothesis should therefore be that nonavian theropod dinosaurs were solitary hunters or, at most, foraged in loose associations. Moreover, we present new evidence from the D. antirrhopus type locality of probable intraspecific aggression in this species. Additionally, our study suggests that some evidence that has previously been proposed in support of highly gregarious, mammal-like behavior in nonavian theropods (e.g., certain theropod-dominated fossil assemblages, preserve...
65 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 2 |
| 2020 | 1 |
| 2019 | 1 |
| 2018 | 1 |
| 2015 | 2 |
| 2011 | 1 |