Re: Tiktaalik roseae - new tetrapod-like vertebrate (Nature)

[Christopher Collinson <thats_mr_annoying_to_you@yahoo.com>]

http://www.latimes.com/news/science/la-040506fossil_lat,0,6819224.story?coll=la-home-headlines

The models made for this discovery are so beyond
awesome, they look like real fish! Does any one know
the artist and if there are more pictures of it
somehwere out in the netverse? 

Cheers,
Christopher


--- Tim Williams <twilliams_alpha@hotmail.com> wrote:

> 
> In today/tomorrow's _Nature_, a new
> missing-link-that-is-no-longer-missing 
> between lobe-finned fishes and tetrapods.  Named
> _Tiktaalik roseae_ (genus 
> name based on a local Inuktitut name for a large,
> freshwater fish) , it is a 
> close relative of _Elpistostege_, and is even closer
> to the origin of 
> tetrapods than _Panderichthys_ is.  Best of all, it
> shows a well-preserved 
> forelimb skeleton.  _Tiktaalik_ is even granted the
> honor of appearing on 
> the _Nature_ cover page.
> 
> Edward B. Daeschler, Neil H. Shubin, and Farish A.
> Jenkins, Jr (2006).  A 
> Devonian tetrapod-like fish and the evolution of the
> tetrapod body plan.  
> Nature 440: 757-763.
> 
> Abstract: "The relationship of limbed vertebrates
> (tetrapods) to lobe-finned 
> fish (sarcopterygians) is well established, but the
> origin of major tetrapod 
> features has remained obscure for lack of fossils
> that document the sequence 
> of evolutionary changes. Here we report the
> discovery of a well-preserved 
> species of fossil sarcopterygian fish from the Late
> Devonian of Arctic 
> Canada that represents an intermediate between fish
> with fins and tetrapods 
> with limbs, and provides unique insights into how
> and in what order 
> important tetrapod characters arose. Although the
> body scales, fin rays, 
> lower jaw and palate are comparable to those in more
> primitive 
> sarcopterygians, the new species also has a
> shortened skull roof, a modified 
> ear region, a mobile neck, a functional wrist joint,
> and other features that 
> presage tetrapod conditions. The morphological
> features and geological 
> setting of this new animal are suggestive of life in
> shallow-water, marginal 
> and subaerial habitats."
> 
> Neil H. Shubin, Edward B. Daeschler, and Farish A.
> Jenkins, Jr (2006). The 
> pectoral fin of _Tiktaalik roseae_ and the origin of
> the tetrapod limb. 
> Nature 440: 764-771.
> 
> Abstract: "Wrists, ankles and digits distinguish
> tetrapod limbs from fins, 
> but direct evidence on the origin of these features
> has been unavailable. 
> Here we describe the pectoral appendage of a member
> of the sister group of 
> tetrapods, _Tiktaalik roseae_, which is
> morphologically and functionally 
> transitional between a fin and a limb. The expanded
> array of distal 
> endochondral bones and synovial joints in the fin of
> _Tiktaalik_ is similar 
> to the distal limb pattern of basal tetrapods. The
> fin of _Tiktaalik_ was 
> capable of a range of postures, including a
> limb-like substrate-supported 
> stance in which the shoulder and elbow were flexed
> and the distal skeleton 
> extended. The origin of limbs probably involved the
> elaboration and 
> proliferation of features already present in the
> fins of fish such as 
> _Tiktaalik_."
> 
> There's also a nice summary:
> 
> Per Erik Ahlberg and Jennifer A. Clack (2006). 
> Palaeontology: A firm step 
> from water to land.  Nature 440: 747-749.
> 
> Cheers
> 
> Tim
> 
> 
> 


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