New subclass of birds from the Cretaceous of South America

Walker, C. A.

doi:10.1038/292051a0

Cited by 159 publications

(124 citation statements)

References 2 publications

Supporting

Mentioning

121

Contrasting

Unclassified

Order By: Relevance

“…Indeed, the Od accumulation bones correspond in morphology and dimensions with those of Enantiornis from Argentina (Walker 1981;Chiappe 1993;Walker and Dyke 2010), strongly suggesting that they come from the same, or a similar, taxon. The proximal section of a humerus (Fig.…”

Section: Descriptionmentioning

confidence: 95%

“…The bicipital crest is robust, rounded, anteriorly projecting and bears a distinct but narrow pneumatic fossa (as in Enantiornis) (Walker and Dyke 2010); the deltopectoral crest is prominent and flat. Incipient pneumatisation of this region via a small pneumatic fossa is shared with similarly sized Argentine enantiornithines, particularly Enantiornis (Walker 1981;Walker and Dyke 2010). An adult scapula from the Od assemblage is robust, straight and with a welldeveloped, straight acromion, a medial longitudinal groove (Fig.…”

Section: Descriptionmentioning

confidence: 99%

See 1 more Smart Citation

A drowned Mesozoic bird breeding colony from the Late Cretaceous of Transylvania

Dyke

Vremir²,

Kaiser

et al. 2012

Naturwissenschaften

View full text Add to dashboard Cite

Despite a rapidly improving fossil record, the reproductive biology of Mesozoic birds remains poorly known: only a handful of undisputed, isolated Cretaceous eggs (some containing embryonic remains) are known. We report here the first fossil evidence for a breeding colony of Mesozoic birds, preserved at the Late Cretaceous (Maastrichtian) Oarda de Jos (Od) site in the Sebeş area of Transylvania, Romania. A lens of calcareous mudstone with minimum dimensions of 80 cm length, 50 cm width and 20 cm depth contains thousands of tightly packed, morphologically homogenous eggshell fragments, seven near-complete eggs and neonatal and adult avialan skeletal elements. Eggshell forms 70-80 % of the matrix, and other fossils are entirely absent. The bones exhibit clear characters of the Cretaceous avialan clade Enantiornithes, and the eggshell morphology is also consistent with this identification. Both taphonomy and lithology show that the components of this lens were deposited in a single flood event, and we conclude that it represents the drowned remains of a larger enantiornithine breeding colony, swamped by rising water, washed a short distance and deposited in a shallow, low-energy pond. The same fate often befalls modern bird colonies. Such a large concentration of breeding birds suggests aquatic feeding in this species, augments our understanding of enantiornithine biology and shows that colonial nesting was not unique to crown birds.

show abstract

Section: Descriptionmentioning

confidence: 95%

Section: Descriptionmentioning

confidence: 99%

A drowned Mesozoic bird breeding colony from the Late Cretaceous of Transylvania

Dyke

Vremir²,

Kaiser

et al. 2012

Naturwissenschaften

View full text Add to dashboard Cite

show abstract

“…For the first half of the clade's history, only very limited enantiornithine skull material had been uncovered (Elzanowski 1974(Elzanowski , 1977Walker 1981;Chiappe 1991) and very little information could be inferred for the clade. Subsequently, dozens of nearly complete skeletons from the Early Cretaceous Jehol Group of northern China were discovered; these have provided unprecedented information elucidating the anatomical and taxonomic diversity and the evolution of Enantiornithes ( Fig.…”

Section: Introductionmentioning

confidence: 99%

A revision of enantiornithine (Aves: Ornithothoraces) skull morphology

O’Connor

Chiappe

2011

Journal of Systematic Palaeontology

113

153

View full text Add to dashboard Cite

Enantiornithines are the most speciose avian clade in the Mesozoic, with a fossil record that nearly spans the Cretaceous; however, with less than half of known taxa preserving skull material, our understanding of their cranial morphology remains incomplete. Here we present a comprehensive overview of the current knowledge of enantiornithine skull anatomy and discuss the range of morphologies known for each of the main cranial elements. The typical enantiornithine skull retains numerous ancestral features such as the absence of fusion among bones, the presence of a postorbital bone, a primitive quadrate with a single headed otic process, an unforked dentary, and teeth. The postorbital in at least one taxon is unreduced, suggesting the existence of a complete infratemporal fenestra and thus an unmodified diapsid skull as in confuciusornithids. The rostrum is well known and shows considerable variation, typical of theropods; however, in terms of rostral proportions, enantiornithines are extremely limited within the modern avian spectrum. Although Late Cretaceous skull material is extremely fragmentary, when compared to Early Cretaceous material it reveals a trend towards more specialized morphologies in younger taxa. The foramen magnum in all taxa points caudally, indicating that the 'flexed' type skull morphology may not have evolved in this group. Enantiornithine teeth show considerable diversity in numbers, size, morphology and placement, ranging from taxa with large teeth found throughout the jaws to taxa with small, rostrally restricted teeth, to the fully edentulous. Despite limited preservation of skull material, a number of trophic specializations can be deduced from the range of preserved morphologies, further hinting at the morphological and ecological diversity of the Cretaceous Enantiornithes.

show abstract

“…The distal humerus (Fig. 3) in Apsaravis displays other features considered characteristic of Enantiornithes 11,13 , including (1) anteroposterior compression and dorsoventral expansion of the distal humerus giving it a`spatulate' aspect 11 ; (2) condyle relative to long axis of the humerus; and (3) the ventral condyle developed as a weak ridge at the (4) angled distal edge of the humerus.…”

mentioning

confidence: 99%

“…The Apsaravis tibiotarsus has a narrow intercondylar groove 13 and barrel-shaped', medially untapering condyles (Fig. 3).…”

mentioning

confidence: 99%