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New hump backed dinosaur suggests
feathers may have emerged in Middle Jurassic

A predatory dinosaur with bony bumps on its arms and a strange hump on its back provides evidence that feathers began to appear earlier than researchers thought, according to a report in Nature today1.

The new species, named Concavenator corcovatus, was about 4 meters long from nose to tail and lived during the Early Cretaceous period, about 130 million years ago. It's the first evidence for feathers found in a branch closely related to Allosaurus. The only other branch of dinosaurs with evidence of feathers is the Coelurosauria (the lineage of T. rex and Velociraptor, the branch heretofore thought to give rise to birds). This new discovery suggests that feathers most likely emerged in the common ancestors of the Coelurosauria and the Concavenator lineages - the Neotetanurae, that lived in the Middle Jurassic (175-161 mya). This discovery also opens the door to the possibility that birds could have descended from the Concavenator lineage rather than the Coelurosauria - a new avenue for investigation emerges!

The article reporting this discovery includes excellent photos of the ulna (fore arm) bone with purported feather quill bumps, and a phylogeny including the new find, with an artist's reconstruction of its likely appearance. This makes a nice example of how science is tentative, and how new data can produce new understanding.

Reference:
1. Ortega, F., Escaso, F. & Sanz, J. L. A bizarre, humped Carcharodontosauria (Theropoda) from the Lower Cretaceous of Spain. Nature 467, 203-206 (8 September 2010).

2. http://www.nature.com/news/2010/100908/full/news.2010.455.html

Figures below from the article in Nature. Reconstruction was kept large for showing details and for sharper display if you plan to use in a PPT presentation.

 a. Forearm bones from the new dinosaur, Concaveenator corcovatus - radius at top, ulna at bottom.

 

 

b. Ulna enlarged, showing series of feather quill knobs (arrows).

c. Dorsal view of ulna from a modern turkey vulture (Cathartes sp.) showing feather quill knobs.

All Scale bars, 1 cm

 
Time-calibrated reduced consensus of the phylogeny of Neotetanurae theropods.
Placement of the new species is shown in red, in a major branch associated with Allosaurus.
Note the Coelurosauria branch on the far left, the group containing all other known feathered dinosaurs, e.g., T. rex and Velociraptor. Assuming that feathers did not emerge separately in those two major branches, it appears that feathers most likely emerged in a common ancestor, in the Neotetanurae at the bottom, during the Middle Jurassic.
Hypothetical flesh reconstruction of  Concaveenator corcovatus