[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: New Archaeorhynchus (basal ornithuromorph) adult specimen described (free pdf)



The pdf is now free (urls are separated):

Min Wang & Zhonghe Zhou (2016)
A new adult specimen of the basalmost ornithuromorph bird
Archaeorhynchus spathula (Aves: Ornithuromorpha) and its implications
for early avian ontogeny.
Journal of Systematic Palaeontology (advance online publication)
DOI:10.1080/14772019.2015.1136968
http: // www.tandfonline.com/doi/full/10.1080/14772019.2015.1136968

pdf:

http: // www.tandfonline.com/doi/pdf/10.1080/14772019.2015.1136968


On Wed, Feb 3, 2016 at 8:50 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
>
> A new paper:
>
> Min Wang & Zhonghe Zhou (2016)
> A new adult specimen of the basalmost ornithuromorph bird
> Archaeorhynchus spathula (Aves: Ornithuromorpha) and its implications
> for early avian ontogeny.
> Journal of Systematic Palaeontology (advance online publication)
> DOI:10.1080/14772019.2015.1136968
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.tandfonline.com_doi_full_10.1080_14772019.2015.1136968&d=CwIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=umvPcx_TpQQxgFfxAD4tcfpakMKi8vjwqrbzO7bp7R4&s=_OfXTYaFq4yvPskzOCP25ujVyy6ZfxeRwL2QNQvbMWg&e=
>  
>
> Most living birds characteristically grow rapidly and reach adult size
> within a year. Nevertheless, little is known about how such an
> advanced developmental strategy evolved despite many discoveries of
> early fossil birds. Here we assess the long-bone histology from a new
> adult specimen of Archaeorhynchus spathula, the basalmost taxon of
> Ornithuromorpha. Ornithuromorpha is the most inclusive clade
> containing extant birds but not the Mesozoic Enantiornithes.
> Histological analysis reveals that the cortex is composed of
> parallel-fibred bone with three lines of arrested growth, indicative
> of slow and annually interrupted growth for this taxon. Such bone
> histology is significantly different from that of other known basal
> ornithuromorphs, but resembles that of enantiornithines, which leads
> us to suggest protracted slow growth in the common ancestor of
> Ornithuromorpha and Enantiornithes. The fusion sequence of the
> tarsometatarsus between Enantiornithes and Ornithuromorpha has long
> been hypothesized to be different and regarded as indicative that
> enantiornithines are not close relatives of ornithuromorphs. Due to a
> lack of fossils recording early ontogenetic stages, little is known
> about the development of the tarsometatarsus in basal ornithuromorphs,
> making this hypothesis impossible to test. Here we show that the
> fusion sequence of the tarsometatarsus in Archaeorhynchus is similar
> to that of enantiornithines, and that the proximal-early fusion in
> tarsometatarsus represents a plesiomorphic trait for basal birds. Our
> findings also shed light on ontogenetic variation of sternal
> morphology, which highlights the importance of ontogeny in the
> taxonomic and phylogenetic study of early birds.