El Rincon de la Esquina

Dinosaurios, Fosiles, Minerales y algunas frikadas


Me and my mutual followers that never seem to actually talk but we like and reblog each other’s posts:


(vía rockahell)


Discovery of Tiktaalik Roseae Fossils Reveals Key Link in Evolution of Hind Limbs in Science Daily Jan. 13, 2014 

You need to understand that although yes, the discovery did lead to this January 8, 2014 publication being reported here, the discovery itself was eight years ago. Carl Zimmer announced the publication of it in his blog, The Loom, on  April 5,2006 in a post called Walking Towards Land

The [2004] discovery of well-preserved pelves [plural of pelvis] and a partial pelvic fin from Tiktaalik roseae, a 375 million-year-old transitional species between fish and the first legged animals, reveals that the evolution of hind legs actually began as enhanced hind fins.

This challenges existing theory that large, mobile hind appendages were developed only after vertebrates transitioned to land.

"Previous theories, based on the best available data, propose that a shift occurred from ‘front-wheel drive’ locomotion in fish to more of a ‘four-wheel drive’ in tetrapods," said Neil Shubin, PhD, Robert R. Bensley Distinguished Service Professor of Anatomy at the University of Chicago and corresponding author of the study, which marks Shubin’s inaugural article as a member of the National Academy of Sciences. “But it looks like this shift actually began to happen in fish, not in limbed animals.”

The Science Daily piece does have nice quotes from Shubin … And:

Shubin, author of the 2009 book Your Inner Fishwill be hosting a three-part TV series based on the book on PBS in April 2014, tracing the origins of the human body through the DNA of living animals and the legacies of now-extinct, but biologically important species such as Tiktaalik roseae.

Carl Zimmer has a long blog post on this called How We Got On Land, Bone by Bone. This has already been reported  on Tumblr by dendroica

Now, let’s turn to the actual paper, in Proceedings of the National Academy of Sciences: “Pelvic girdle and fin of Tiktaalik roseae”

Neil H. Shubin, Edward B. Daeschler, and Farish A. Jenkins, Jr.
PNAS 2014/01/08   doi: 10.1073/pnas.1322559111
Freely available online [in PDF format] through the PNAS open access option.

Significance [from Proceedings of the National Academy of Sciences]

The earliest tetrapods have robust limbs, particularly hind limbs that are enlarged and supported by a number of modifications to the pelvic girdle. In contrast, the closest relatives of tetrapods maintain small and weakly ossified pelvic appendages as compared with the pectorals.

This observation has led to the “front wheel drive” hypothesis that held that the closest relatives of tetrapods emphasized pectoral support and locomotion whereas significant pelvic support and locomotion was a tetrapod innovation. The discovery of pelvic girdle and fin material of the tetrapodomorph Tiktaalik roseae reveals a transitional stage in the origin of the pelvic girdle and appendage: although retaining primitive skeletal architecture, these elements are enhanced in size and robusticity much like tetrapods.

SOURCE: Pelvic girdle and fin of Tiktaalik roseae

[1][2] The holotype (the type specimen that defines the species) of Tiktaalik roseae. Photo by Nathan Pierson/ANSP.

[3] Dr. Neil Shubin with a model of Tiktaalik roseae. © The Field Museum, Photographer John Weinstein

[4] An updated illustration of Tiktaalik roseae in its natural environment. (Credit: University of Chicago, Neil Shubin)

(vía woodtux)

Bombones de Chocolate!!!

Bombones de Chocolate!!!

Protoceratops, Exposición Tesoros del desierto del Gobi

  • Protoceratops Andrewsi
  • Ornithischia, Ceratopsia, Protoceratopsidae
  • Cretácico Superior, Piso Djadokhtian, 85-80 m.a
  • Expedición Paleontológica Mongolia y URSS, 1976. 
  • Tugrugeen Shireh, Gobi centromeridional, Mongolia