Saturday, April 7, 2012

Yutyrannus - Not Feathers
"As usual, the main gee-whiz points about Yutyrannus are already being widely discussed. We’ve known for a while (since the publication of Dilong paradoxus in 2004) that at least some tyrannosauroids possess stage 1 feathers (Xu et al. 2004). That is, filamentous integumentary structures that seem to be evolutionary precursors to the true, complex feathers that evolved elsewhere within coelurosaurian theropods. Yutyrannus is another feathery/filamenty tyrannosauroid, but it’s remarkable in being huge – it’s about 9 m long, meaning that here is the first GIANT feathery/filamenty tyrannosauroid."
"Feather evolution was broken down into the following stages by Xu and Guo in 2009:1. Single filament2. Multiple filaments joined at their base. 3. Multiple filaments joined at their base to a central filament4. Multiple filaments along the length of a central filament5. Multiple filaments arising from the edge of a membranous structure6. Pennaceous feather with vane of barbs and barbules and central rachis7. Pennaceous feather with an asymmetrical rachis8. Undifferentiated vane with central rachis"

Notice the unsupported part:
"Yutyrannus is another feathery/filamenty tyrannosauroid."

Yutyrannus is in no way "feathery". 

If people believed that birds were descended from pigs, they would call these pig bristles, "protofeathers":

But that is the sort of thing they claim now, in regard to the "filaments" (bristles) found on dinosaurs.
"Darwinian  approaches to the  origin  of feathers, exemplified by Bock (1965),  have hypothesized a microevolutionary and functional continuum between  feathers and a hypothesized  antecedent structure (usually an elongate scale). Feathers, however, are hierarchically complex  assemblages of numerous evolutionary novelties—the feather follicle, tubular feather germ, feather branched structure,  interacting differentiated barbules—that have no homolog in any antecedent structures (Brush  1993, 1996, 2000; Prum  1999).
Genuine evolutionary novelties are distinct from simple microevolutionary changes in that they are qualitatively or categorically different from any antecedent or homonomous structure (Nitecki  1990; Mu¨ ller and  Wagner  1991; Raff 1996)."

So there is as much connection between pig bristles and feathers as there is between dinosaur "filaments" and feathers. In both cases, all the intermediates (all the "hierarchically complex  assemblages of numerous evolutionary novelties") are missing.
In one case, it would be a jump from pig bristle right to feather.
In the other case, it is a jump from dinosaur "filament" right to feather.

More from Darren Naish:
"I must confess to being somewhat sceptical of the tyrannosauroid identification for Yutyrannus. I reviewed this paper (to those who don’t know: I did my PhD thesis on basal tyrannosauroids), and noted immediately that Yutyrannus actually resembles carcharodontosaurian allosauroids in some respects."

Porcupine with multi-coloured bristles:
Filamentous integumentary structures are preserved in all three specimens. Those preserved in ZCDM V5000 are evidently associated with the posterior caudal vertebrae. As preserved, they are parallel to each other and form an angle of about 30u with the long axis of the tail. The filaments are at least 15 cm long. They are too densely packed for it to be possible to determine whether they are elongate broad filamentous feathers (EBFFs) like those seen in the therizinosauroid Beipiaosaurus, slender monofilaments, or compound filamentous structures. Those of ZCDM V5001 are near the pelvis and pes. They are filamentous structures, but morphological details are not preserved

Thursday, April 5, 2012

Another claim of a "feathered dinosaur"
The discovery of the largest known feathered dinosaur was announced by scientists in China on Wednesday. Similar in size and shape to Tyrannosaurus rex, palaeontologists at the Chinese academy of sciences in Beijing have named the new species Yutyrannus huali, meaning "beautiful feathered tyrant". At nine metres long and weighing more than 1.4 tonnes, it is also the largest feathered animal ever discovered – either alive or extinct.
Local farmers found three specimens in a small quarry in the Liaoning province of north-east China. Palaeontologists estimate that they are 125m years old, dating from the early Cretaceous period, and they believe that, like Tyrannosaurus rex, the animals hunted in packs. The three were found alongside the remains of a sauropod dinosaur that the researchers think they may have been hunting when they died.
I will say a few things about this in the next post.
Needless to say, this is not a feathered dinosaur.