by This is one of most fascinating finds I have ever witnessed in all of my exposure to paleontology! Enjoy! I sure am.
LINK
Science 16 September 2011:
Vol. 333 no. 6049 pp. 1619-1622
DOI: 10.1126/science.1203344
"A Diverse Assemblage of Late Cretaceous Dinosaur and Bird Feathers from Canadian Amber"
Ryan C. McKellar, Brian D. E. Chatterton, Alexander P. Wolfe, Philip J. Currie
Abstract:
The fossil record of early feathers has relied on carbonized compressions that lack fine structural detail. Specimens in amber are preserved in greater detail, but they are rare. Late Cretaceous coal-rich strata from western Canada provide the richest and most diverse Mesozoic feather assemblage yet reported from amber. The fossils include primitive structures closely matching the protofeathers of nonavian dinosaurs, offering new insights into their structure and function. Additional derived morphologies confirm that plumage specialized for flight and underwater diving had evolved in Late Cretaceous birds. Because amber preserves feather structure and pigmentation in unmatched detail, these fossils provide novel insights regarding feather evolution.
The currently accepted (11, 12) evolutionary-developmental model for feathers (Fig. 1A) consists of a stage I morphology characterized by a single filament: This unfurls into a tuft of filaments (barbs) in stage II. In stage III, either some tufted barbs coalesce to form a rachis (central shaft) (IIIa), or barbules (segmented secondary branches) stem from the barbs (IIIb); then, these features combine to produce tertiary branching (IIIa+b). Barbules later differentiate along the length of each barb, producing distal barbules with hooklets at each node to interlock adjacent barbs and form a closed pennaceous (vaned) feather (stage IV). Stage V encompasses a wide range of additional vane and subcomponent specializations. Most modern birds possess stage IV or V feathers or secondary reductions from these stages (11, 16). Modern feathers exhibit a range of morphologies that are associated with their various functions and remain discernible in some of their finest subunits, the barbules (17). This is particularly important in the study of amber-entombed feathers because preservation is biased toward feather subcomponents, which provide the basis for our morphological comparisons.
.Canadian amber provides examples of stages I through V of Prum’s (11) evolutionary-developmental model for feathers. None of the additional morphotypes observed in compression fossils of nonavian dinosaurs (8, 15) or amber (4) were found here, suggesting that some morphotypes may not represent distinct evolutionary stages, or may not have persisted into the Late Cretaceous. The snapshot of Campanian feather diversity from Canadian amber is biased toward smaller feathers, subcomponents of feathers, feathers that are molted frequently, and feathers in body positions that increase their likelihood of contacting resin on tree trunks. Despite these limitations, the assemblage demonstrates that numerous evolutionary stages were present in the Late Cretaceous, and that plumage already served a range of functions in both dinosaurs and birds
Special thanks to SteveF over on talkrat for posting the detailed info above. If someone can get a copy of the full paper and forward it to me I would very grateful.
RS
