Axial and appendicular pneumaticity in<i>Archaeopteryx</i>

Christiansen, Per; Bonde, Niels

doi:10.1098/rspb.2000.1311

Cited by 25 publications

(31 citation statements)

References 23 publications

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“…Pneumaticity has been recognized in the skull, cervical and thoracic vertebrae and pelvis of Archaeopteryx (Britt et al 1998;Christiansen and Bonde 2000). Jeholornis has not only preserved pneumaticity in various thoracic vertebrae but also in the sternum.…”

Section: Discussionmentioning

confidence: 97%

Jeholornis compared to Archaeopteryx, with a new understanding of the earliest avian evolution

Zhou

Zhang

2003

Naturwissenschaften

110

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The recently reported Jeholornis represents the only known bird with a complete long skeletal tail except for Archaeopteryx. Two newly discovered specimens referable to Jeholornis provide some important new information about its anatomy. The tail of Jeholornis is much longer than that of Archaeopteryx and comprises a maximum of 27 caudal vertebrae compared with only 23 in Archaeopteryx. More interestingly, the tail feathers are shaped more like those of dromaeosaurs than those of Archaeopteryx. We conclude that the common ancestor of birds must have a more primitive tail than that in Archaeopteryx, confirming the side branch position of Archaeopteryx in the early avian evolution. The synsacrum is composed of six sacrals, representing a transitional stage between Archaeopteryx and more advanced birds. The scapula of Jeholornis has a dorso-laterally exposed glenoid facet, and the coracoid has a supracoracoid foramen. The presence of a pair of fenestrae in the sternum of Jeholornis has further implications for the air-sac system in early birds.

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Section: Discussionmentioning

confidence: 97%

Jeholornis compared to Archaeopteryx, with a new understanding of the earliest avian evolution

Zhou

Zhang

2003

Naturwissenschaften

110

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“…Evidence for PSP in Archaeopteryx is equivocal (contra Britt et al, '98;Christiansen and Bonde, 2000;see O'Connor, 2006;Mayr et al, 2007). Foramina in the vertebrae and pelvic elements are not clearly pneumatic.…”

Section: Shared Developmental Pathways and The Origin(s) Of Air Sacs mentioning

confidence: 92%

“…Postcranial skeletal pneumaticity (PSP) is also present in most saurischian dinosaurs and pterosaurs and was recognized in these animals from very early discoveries (Owen, 1857;Seeley, 1870). After a century of infrequent study (Janensch,'47), PSP in fossil archosaurs has received increasing attention in the past decade and a half (Britt, '97;Britt et al, '98;Christiansen and Bonde, 2000;Wedel et al, 2000;Bonde and Christiansen, 2003;Wedel, 2003aWedel, ,b, 2005Wedel, , 2006Wedel, , 2007O'Connor and Claessens, 2005;O'Connor, 2006;Schwarz and Fritsch, 2006;Schwarz et al, 2007;Sereno et al, 2008).…”

mentioning

confidence: 97%

Evidence for bird‐like air sacs in saurischian dinosaurs

2009

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Among extant tetrapods, pneumatic postcranial bones are only present in birds, and they are osteological correlates of the diverticular lungs and pulmonary air sacs. The presence of postcranial pneumaticity in sauropod and theropod dinosaurs suggests that some form of air sac system was also present in the dinosaurian ancestors of birds. In particular, anatomical and evolutionary patterns of pneumatization in nonavian saurischian dinosaurs are diagnostic for specific air sacs, including the cervical, clavicular, and abdominal air sacs. Pneumatic hiatuses are gaps in the pneumatization of the vertebral column and indicate pneumatization from multiple sources. A pneumatic hiatus in Haplocanthosaurus provides additional support for the presence of abdominal air sacs in sauropods. The origins of postcranial pneumaticity in archosaurs are enigmatic because the earliest putative traces of pneumaticity are difficult to distinguish from skeletal imprints of other soft tissues. Nevertheless, several lines of evidence suggest that air sac-driven lung ventilation was primitive for Saurischia.

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“…There are air sacs in the vertebrae, at least in the cervicals and some dorsals, in most modern birds, but there is a large variation in extent and distribution within the skeleton. There are pleurocoels in most theropods (also present in Archaeopteryx -see Britt et al 1998 andBonde 2000 -although we subsequently failed to find good evidence for pneumatic foramina in the third species [Bonde 1996], A. bavarica Wellnhofer 1993 and advanced sauropods (see below), and similarly in many pterosaurs. But there is not a convincing overview of the distribution within this group (Padian 1983a), although Bennett (1994) and Unwin & Lti (1997) used pneumatic characters in discussions of pterodactyloid systematics.…”

Section: Homology Of the Air Diverticulae In Pterosaurs And Birdsmentioning

confidence: 94%

The detailed anatomy of Rhamphorhynchus : axial pneumaticity and its implications

Bonde¹,

Christiansen²

2003

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An acid- and transfer-prepared, juvenile Rhamphorhynchus muensteri, despite some fragmentation, is in an excellent state of three-dimensional preservation, exposing exquisite anatomical details hitherto unknown in other pterosaurs. Here we describe the axial pneumatizations of the cervical and anterior dorsal vertebrae and the sternum. The interior of the cervical centra is subdivided into a pair of large camerae, presumably by air sacs entering by large pleurocoels in the sides of the centra. This so-called ‘camerate’ type of pneumatization is hitherto unknown in pterosaurs. Another excavation enters from the ventral side into the base of the neural arch and stretches between the pre- and postzygapophyses. This type of cavity also penetrates from the ventral side into the base of the first few transverse processes of the dorsal vertebrae, although these lack central pleurocoels. The cristospine also has a complex pneumatic foramen.Skeletal pneumaticity is most probably a result of a highly derived pulmonary system, as in extant birds. Morphologically similar pneumatic features are present in most saurischian dinosaurs and it is possible that they are the result of convergence. Because basal members of the various groups, including Triassic pterosaurs, appear to lack skeletal pneumaticity, convergence seems likely, although the stem-ornithodiran parsimoniously possessed a more bird-like than ‘reptile’-like pulmonary system, albeit non-invasive. This points to possible tachymetabolism in these forms, which is in accord with the distribution of other factors such as integumentary structures and bone histology. It is concluded that evolution of this suite of advanced features, surprisingly, was among the earliest events in the ornithodiran lineage soon after it split off from its crocodilian sister-group.

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Axial and appendicular pneumaticity inArchaeopteryx

Cited by 25 publications

References 23 publications

Jeholornis compared to Archaeopteryx, with a new understanding of the earliest avian evolution

Jeholornis compared to Archaeopteryx, with a new understanding of the earliest avian evolution

Evidence for bird‐like air sacs in saurischian dinosaurs

The detailed anatomy of Rhamphorhynchus : axial pneumaticity and its implications

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