Forum Dinozaury.com

Xing Xu, James M. Clark, Jinyou Mo, Jonah Choiniere, Catherine A. Forster, Gregory M. Erickson, David W. E. Hone, Corwin Sullivan, David A. Eberth, Sterling Nesbitt, Qi Zhao, Rene Hernandez, Cheng-kai Jia, Feng-lu Han & Yu Guo (2009) "A Jurassic ceratosaur from China helps clarify avian digital homologies" Nature 459, 940-944 (18 June 2009) | doi:10.1038/nature08124;

Theropods have traditionally been assumed to have lost manual digits from the lateral side inward, which differs from the bilateral reduction pattern seen in other tetrapod groups. This unusual reduction pattern is clearly present in basal theropods, and has also been inferred in non-avian tetanurans based on identification of their three digits as the medial ones of the hand (I-II-III). This contradicts the many developmental studies indicating II-III-IV identities for the three manual digits of the only extant tetanurans, the birds. Here we report a new basal ceratosaur from the Oxfordian stage of the Jurassic period of China (156–161 million years ago), representing the first known Asian ceratosaur and the only known beaked, herbivorous Jurassic theropod. Most significantly, this taxon possesses a strongly reduced manual digit I, documenting a complex pattern of digital reduction within the Theropoda. Comparisons among theropod hands show that the three manual digits of basal tetanurans are similar in many metacarpal features to digits II-III-IV, but in phalangeal features to digits I-II-III, of more basal theropods. Given II-III-IV identities in avians, the simplest interpretation is that these identities were shared by all tetanurans. The transition to tetanurans involved complex changes in the hand including a shift in digit identities, with ceratosaurs displaying an intermediate condition.

Justyna pisze: :D

Ag.Ent pisze:No i przede wszystkim jest tam link do abstraktu ;)

http://www.nature.com/nature/journal/v4 ... 08124.html

[umieszczony (widocznie zakamuflowany ) w doi w tytule cytowanej przeze mnie pracki nazuul]

EDIT:
Faktycznie, ukryty jak nie wiem co No ale nie zauważyłem wcześniej

Bill Parker pisze:As Tom Holtz noted to me in an earlier e-mail message....this is a "ceratosaur convergent on Effigia (a Triassic pseudosuchian): Truly weird!". I could not have summed it up any better!

Mirror.co.uk w tytule pisze:Fossil-hunters find the 'missing link' between dinosaurs and birds

nazuul pisze:Art jutro w (no niestety ) Nature.

nazuul pisze:PS Ciekawe wyniki analizy kladystycznej (strict consensus) z SI:
- nowoopiany rodzaj to takson siostrzany elafrozaura
- Berberosaurus dilofozaurydem
Trochę "dalsze":
- Spinosauridae
- (Compsognathus + Coelurus) Sinosauropteryx

Wyniki z Figure S7 i S8 są jeszcze dziwniejsze

hanys pisze:

nazuul pisze:Art jutro w (no niestety ) Nature.

no, suplementy są ciekawsze niż sam artykuł

hanys pisze:i silezaur jest dinozaurem

nazuul pisze:O widzę kolega przeczytał już jutrzejszą prasę. Jak w serialu "Zdarzyło się jutro"?