Notice of new dinosaurian reptiles from the Jurassic formation

Marsh, O. C.

doi:10.2475/ajs.s3-14.84.514

Cited by 117 publications

(57 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous workers (e.g., Cope, 1877;Marsh, 1877;Seeley, 1901;Mü ller, 1908;Romer, 1966;Currey and Alexander, 1985;Carrano and O'Connor, 2005) have emphasized the densityreducing effect of skeletal pneumatization in fossil archosaurs. From studies of extant birds, pneumatization proceeds by the replacement of trabecular bone and marrow with air sac diverticula (Bremer, 1940b;King and Kelly, 1956;King, 1957;Schepelmann, 1990;Brackmann, 1991), resulting in a significant reduction in the density of a given bone.…”

Section: Nonpulmonary Roles Of Postcranial Pneumaticitymentioning

confidence: 99%

See 1 more Smart Citation

Postcranial pneumaticity: An evaluation of soft-tissue influences on the postcranial skeleton and the reconstruction of pulmonary anatomy in archosaurs

2006

View full text Add to dashboard Cite

Postcranial pneumaticity has been reported in numerous extinct sauropsid groups including pterosaurs, birds, saurischian dinosaurs, and, most recently, both crurotarsan and basal archosauriform taxa. By comparison with extant birds, pneumatic features in fossils have formed the basis for anatomical inferences concerning pulmonary structure and function, in addition to higher-level inferences related to growth, metabolic rate, and thermoregulation. In this study, gross dissection, vascular and pulmonary injection, and serial sectioning were employed to assess the manner in which different soft tissues impart their signature on the axial skeleton in a sample of birds, crocodylians, and lizards. Results from this study indicate that only cortical foramina or communicating fossae connected with large internal chambers are reliable and consistent indicators of pneumatic invasion of bone. As both vasculature and pneumatic diverticula may produce foramina of similar sizes and shapes, cortical features alone do not necessarily indicate pneumaticity. Noncommunicating (blind) vertebral fossae prove least useful, as these structures are associated with many different soft-tissue systems. This Pneumaticity Profile (PP) was used to evaluate the major clades of extinct archosauriform taxa with purported postcranial pneumaticity. Unambiguous indicators of pneumaticity are present only in certain ornithodiran archosaurs (e.g., sauropod and theropod dinosaurs, pterosaurs). In contrast, the basal archosauriform Erythrosuchus africanus and other nonornithodiran archosaurs (e.g., parasuchians) fail to satisfy morphological criteria of the PP, namely, that internal cavities are absent within bone, even though blind fossae and/or cortical foramina are present on vertebral neural arches. An examination of regional pneumaticity in extant avians reveals remarkably consistent patterns of diverticular invasion of bone, and thus provides increased resolution for inferring specific components of the pulmonary air sac system in their nonavian theropod ancestors. By comparison with well-preserved exemplars from within Neotheropoda (e.g., Abelisauridae, Allosauroidea), the following pattern emerges: pneumaticity of cervical vertebrae and ribs suggests pneumatization by lateral vertebral diverticula of a cervical air sac system, with sacral pneumaticity indicating the presence of caudally expanding air sacs and/or diverticula. The identification of postcranial pneumaticity in extinct taxa minimally forms the basis for inferring a heterogeneous pulmonary system with distinct exchange and nonexchange (i.e., air sacs) regions. Combined with inferences supporting a rigid, dorsally fixed lung, osteological indicators of cervical and abdominal air sacs highlight the fundamental layout of a flow-through pulmonary apparatus in nonavian theropods.

show abstract

Section: Nonpulmonary Roles Of Postcranial Pneumaticitymentioning

confidence: 99%

“…Yet others merely cite the necessity of large animals to reduce body mass, as large fossae and internal cavities within bone (regardless of whether or not the author promoted an air sac origin for them) provide a means of maintaining strength with minimizing materials (Cope, 1877;Marsh, 1877;Osborn, 1899;Romer, 1966;Carrano and O'Connor, 2005).…”

mentioning

confidence: 99%

Postcranial pneumaticity: An evaluation of soft-tissue influences on the postcranial skeleton and the reconstruction of pulmonary anatomy in archosaurs

2006

View full text Add to dashboard Cite

show abstract

“…7). Those of Apatosaurus Marsh, 1877, for example, are anteroposteriorly short and dorsoventrally tall, and have short, robust cervical ribs mounted far ventral to the centra; the cervical centra of Isisaurus colberti (Jain & Bandyopadhyay, 1997) are even shorter anteroposteriorly, but have more dorsally located cervical ribs; by contrast, the cervical vertebrae of Erketu ellisoni Ksepka & Norell, 2006 are relatively much longer and lower, and have long, thin cervical ribs mounted only slightly ventral to the centra, which are sigmoid rather than cylindrical. Towards the middle ground of these extremes fall the cervical vertebrae of Giraffatitan , which are anteroposteriorly longer and dorsoventrally shorter than those of Apatosaurus, but not as anteroposteriorly long or as dorsoventrally short as those of Erketu .…”

Section: Architecture Of Sauropod Necksmentioning

confidence: 99%

“…7.5), although the spines are higher in posterior cervicals. It is possible that in the posterior cervicals of some Apatosaurus ajax Marsh, 1877 specimens, the epipophyses are higher than the metapophyses (Fig. 7.1), but it is difficult to be sure as the vertebrae that seem to most closely approach this condition are at least partly reconstructed in plaster (Barbour, 1890, figure 1).…”

Section: Architecture Of Sauropod Necksmentioning

confidence: 99%

Why sauropods had long necks; and why giraffes have short necks

Taylor

Wedel

2013

PeerJ

View full text Add to dashboard Cite

The necks of the sauropod dinosaurs reached 15 m in length: six times longer than that of the world record giraffe and five times longer than those of all other terrestrial animals. Several anatomical features enabled this extreme elongation, including: absolutely large body size and quadrupedal stance providing a stable platform for a long neck; a small, light head that did not orally process food; cervical vertebrae that were both numerous and individually elongate; an efficient air-sac-based respiratory system; and distinctive cervical architecture. Relevant features of sauropod cervical vertebrae include: pneumatic chambers that enabled the bone to be positioned in a mechanically efficient way within the envelope; and muscular attachments of varying importance to the neural spines, epipophyses and cervical ribs. Other long-necked tetrapods lacked important features of sauropods, preventing the evolution of longer necks: for example, giraffes have relatively small torsos and large, heavy heads, share the usual mammalian constraint of only seven cervical vertebrae, and lack an air-sac system and pneumatic bones. Among non-sauropods, their saurischian relatives the theropod dinosaurs seem to have been best placed to evolve long necks, and indeed their necks probably surpassed those of giraffes. But 150 million years of evolution did not suffice for them to exceed a relatively modest 2.5 m.

show abstract

“…We also revise the identifications of the previously described pedal phalanges. These corrections were made based on comparisons with phalanges of Allosaurus fragilis [12], Neovenator salerii [13] and the emu ( Dromaius novaehollandiae ). The pedal phalanges described in the initial description of Australovenator , when assigned to their correct positions, represent left pedal phalanx, IV-1 and right pedal phalanges I-2, II-3, III-2, III-3, IV-4 and IV-5.…”

Section: Introductionmentioning

confidence: 99%

New Australovenator Hind Limb Elements Pertaining to the Holotype Reveal the Most Complete Neovenatorid Leg

et al. 2013

View full text Add to dashboard Cite

We report new skeletal elements pertaining to the same individual which represents the holotype of Australovenator wintonensis, from the ‘Matilda Site’ in the Winton Formation (Upper Cretaceous) of western Queensland. The discovery of these new elements means that the hind limb of Australovenator is now the most completely understood hind limb among Neovenatoridae. The new hind limb elements include: the left fibula; left metatarsal IV; left pedal phalanges I-2, II-1, III-4, IV-2, IV-3; and right pedal phalanges, II-2 and III-1. The detailed descriptions are supported with three dimensional figures. These coupled with the completeness of the hind limb will increase the utility of Australovenator in comparisons with less complete neovenatorid genera. These specimens and the previously described hind limb elements of Australovenator are compared with other theropods classified as neovenatorids (including Neovenator, Chilantaisaurus, Fukuiraptor, Orkoraptor and Megaraptor). Hind limb length proportion comparisons indicate that the smaller neovenatorids Australovenator and Fukuiraptor possess more elongate and gracile hind limb elements than the larger Neovenator and Chilantaisaurus. Greater stride lengths to body size exist in both Fukuiraptor and Australovenator with the femur discovered to be proportionally shorter the rest of the hind limb length. Additionally Australovenator is identified as possessing the most elongate metatarsus. The metatarsus morphology varies with body size. The larger neoventorids possess a metatarsus with greater width but shorter length compared to smaller forms.

show abstract

Notice of new dinosaurian reptiles from the Jurassic formation

Cited by 117 publications

References 0 publications

Postcranial pneumaticity: An evaluation of soft-tissue influences on the postcranial skeleton and the reconstruction of pulmonary anatomy in archosaurs

Postcranial pneumaticity: An evaluation of soft-tissue influences on the postcranial skeleton and the reconstruction of pulmonary anatomy in archosaurs

Why sauropods had long necks; and why giraffes have short necks

New Australovenator Hind Limb Elements Pertaining to the Holotype Reveal the Most Complete Neovenatorid Leg

Contact Info

Product

Resources

About