– Glimpse into how feath­ers evolved

The am­ber- en­cased spec­i­men is the first con­firmed to be from a dino. APRIL REESE re­ports.

Cosmos - - Digest -

About 99 mil­lion years ago, in what is now north­ern Burma, a tiny di­nosaur about the size of a spar­row met its end, its tail en­snared in tree sap.

But what was a fa­tal mis­step for the Cre­ta­ceous-era di­nosaur turned out to be a gift to science. The am­ber-en­cased tail, ex­tracted from its rest­ing place in the Hukawng Val­ley by gem min­ers, has of­fered sci­en­tists the first 3-D view of a com­pletely in­tact, feath­ered di­nosaur tail.

“In the past, feath­ers have been found in am­ber, but their source an­i­mals have been dif­fi­cult to pin down,” says palaeon­tol­o­gist Lida Xing of the China Univer­sity of Geos­ciences, who was tipped off about the sam­ple by an am­ber dealer. Xing and his team de­scribed the find in Cur­rent Bi­ol­ogy in De­cem­ber.

The tail was flex­i­ble, with eight ar­tic­u­lated ver­te­brae. This ruled out the pos­si­bil­ity that it be­longed to an an­ces­tor of birds, whose tail ver­te­brae, like those of mod­ern birds, were fused.

The well-pre­served di­nosaur tail, which likely be­longed to a ju­ve­nile coelurosaur, re­veals new de­tails about how feath­ers evolved.

A CT scan of the spec­i­men showed feath­ers ran down the tail, but they lacked the well-de­vel­oped cen­tral shaft, or rachis, found in feath­ers used in flight. That sup­ports the the­ory that an­i­mals first de­vel­oped feath­ers not to fly but per­haps for cam­ou­flage, or at­tract­ing mates.

CREDIT: ROYAL SASKATCHEWAN MU­SEUM / R.C. MCKEL­LAR

A close-up view of the first in­tact feath­ered di­nosaur tail ever to be found.

CREDIT: LIDA XING

Eight jointed ver­te­brae show the tail be­longed to a tiny di­nosaur, not a bird.

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