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Wednesday, July 18, 2012

The "Ancestor of All Dinosaurs" Might Have Had Dinofuzz (Updated)


Sciurumimus albersdoerferi.jpg
See below for an update about the quote from Witmer's paper, "Fuzzy origins for feathers," on Caudipteryx, a fossil (which was a bird, not a dinosaur) that did have true pennaceous feathers.
The media that loyally serve Big Science are at it again, overstating the finds of a scientific paper to promote an evolutionary icon. This time, the icon is feathered dinosaurs, representing the purported ancestral relationship between dinos and birds. A recent article in Science News claims, "All dinosaurs may have had feathers," because a newly discovered fossil dinosaur supposedly "sports long, fine plumage." Looking at the find, however, shows that it's nothing more than a classic example of what critics affectionately call "dinofuzz." This is all-but-admitted in the technical paper, published in Proceedings of the National Academy of Sciences, which states:
Here we report an exceptionally preserved skeleton of a juvenile megalosauroid,Sciurumimus albersdoerferi n. gen., n. sp., from the Late Jurassic of Germany, which preserves a filamentous plumage at the tail base and on parts of the body. These structures are identical to the type 1 feathers that have been reported in some ornithischians, the basal tyrannosaur Dilong, the basal therizinosauroidBeipiaosaurus, and, probably, in the basal coelurosaur Sinosauropteryx.
(Oliver W. M. Rauhut, Christian Foth, Helmut Tischlinger, and Mark A. Norell, "Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany," Proceedings of the National Academy of Sciences (2012))
But of course these "type 1 feathers" aren't really true birdlike feathers. As one paper in Naturenoted, they are hairlike structures sometimes called "dinofuzz":
And indeed, Tianyulong doesn't have true pennaceous feathers. It has long filaments, very similar to what have been called "protofeathers" or, more non-committally, "dinofuzz." These filaments are evident in some theropods such asCaudipteryx that have true pennaceous feathers, but are also found in a range of other theropods that lack definitive feathers, such as the basal coelurosaurSinosauropteryx, the therizinosauroid Beipiaosaurus and the basal tyrannosauroidDilong.
(Lawrence M. Witmer, "Fuzzy origins for feathers," Nature, Vol. 458:293-295 (March 19, 2009). Note: See my update below for an explanation of why Caudipteryx is irrelevant to understanding this fossil.)
In other words, the fossil structures on this new dinosaur are being compared to those of species that "lack definitive feathers." They are not "true pennaceous feathers," but rather are best viewed as "filaments" or "dinofuzz." So much for the claim that this was a feathered dinosaur. The truth comes out later in the paper:
The protofeathers probably are monofilaments, because no branching patterns are visible in the well preserved, long filaments above the tail; apparent branching patterns in a few places probably are the result of compaction of these structures. Because of the state of preservation, it cannot be established if these structures were hollow.
Likewise, the Science News piece admits at the bottom of the article: "Unlike modern feathers, these 'protofeathers' or 'type 1 feathers' look like simple strands of hair."
Even if this fossil did have feathers, it's still not clear how that would imply "all dinosaurs" might have had feathers. Because this dinosaur comes from a different group from the one that is said to have led to birds, researchers say it "suggests that the ancestor of all dinosaurs might have been a feathered animal." That argument might add up if you make a bunch of evolutionary assumptions -- namely common descent of all dinosaurs in the first place. But this specimen itself is only about 150 million years old -- far later than the time period in which dinosaurs themselves originated. Dinosaurs are thought to have evolved before 230 million years ago, but as a different paper in Science admitted last year, the fossil record doesn't document the evolution of major dinosaur groups:
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