Little Tyrannosaur with Proto-Feathers Found
National Geographic News wasted no time; a day before a report of another Chinese dinosaur with feathery-like structures was published in Nature,1 they already had color artwork on their news page, trumpeting the title, “T. Rex Cousin Had Feathers.” Yet Nature itself seemed ho-hum about the announcement. It was neither the cover story, nor mentioned in any news briefs in the journal. Though Nature Science Update was proud of the find, it hastened to add that the proto-feathers, as some are calling them, “are not what we would recognise as feathers today, but are their evolutionary precursors. Rather than having a central shaft and barbs, they are single flexible filaments that would have covered the dinosaur’s body like hair.” Next day, Science2 was more interested in its advanced cranium than its fuzz, and mentioned nothing about it being an ancestor of feathers or flight.
A look at the illustrations in the scientific paper confirms the impression that calling these “proto-feathers” is a stretch. Any suggestion that these “integumentary structures” even had branches at all is unclear; they look like narrow, overlapping stripes on the rock, and there is no way to tell how they were attached to the skin. The filaments are only about 2 cm long and were found related to the tail and jaw bones. The team that discovered Sinornithosaurus, another “feathered” dinosaur, admitted in 2001 that “Despite these similarities, homology between the integumental filaments of Sinornithosaurus and avian feathers has been questioned.” The team that reported this new find, named Dilong paradoxus, only referred back to that paper with a cautious statement that such “filamentous integumentary structures in Jehol theropods have been interpreted as protofeathers.”
They suggest that these structures might have provided thermal insulation. These beasts, about the size of large dogs, may have had trouble storing heat. Big animals, like teenage T. rex monsters (see 08/11/2004 headline), have trouble getting rid of it – that’s why elephants lose their baby hair as they grow. They did not give any indication the filaments were related to the origin of flight in any way. Another problem is that Dilong is classified as “early” in the evolution of dinosaurs, and it already had some “derived” features (i.e., fully evolved, similar to those of later descendants), while other contemporaneous groups lacked them. “The distribution of postcranial pneumatization” [hollowness in skeletal bones], for instance, “is thus very complex among coelurosaurians, rather than displaying a continuous evolutionary trend along the line to birds.”
The bottom line: strange filaments apparently associated with a small, new kind of tyrannosaurid dinosaur have been found well preserved in Liaoning province, China, but no one knows quite what to make of them. They appear early on in the tyrannosaurid lineage, but are not yet known among Cretaceous monsters like T. rex. The filaments do not establish any unambiguous phylogenetic link to modern bird feathers except for superficial similarities. They look more like hair than feathers, and probably functioned as insulation.
1Xu, Norell et al., “Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids,” Nature 431, 680 – 684 (07 October 2004); doi:10.1038/nature02855.
2Erik Stokstad, “T. rex Clan Evolved Head First,” Science, Vol 306, Issue 5694, 211, 8 October 2004, [DOI: 10.1126/science.306.5694.211a].
This critter was no more evolving into a bird than a porcupine is, but news outlets like National Geographic are so eager to prove birds evolved from dinosaurs, you can practically sense them chomping at the bit to leap into the air themselves. Mark Norell (on the discovery team) said that Jurassic Park IV will probably portray all the monsters with feathers instead of scales. We’ve learned to be cautious about claims of feathered dinosaurs evolving into birds (see 05/06/2004, 05/19/2003 and 11/21/2002headlines, for instance). It’s going to take a lot more than a few scratch-lines on rock to make this story stick.
Since dinosaurs are not all that similar to living reptiles and are all extinct, we should be open to any piece of evidence that helps us understand what they looked like: skin impressions, tracks, and now these filaments. If the filaments helped keep the little doggy dinosaurs warm, like hair does, then they were not evolving into something else; they had a function. Perhaps the young had some kind of downy covering to retain heat and lost it as adults. Avian feathers, on the other hand, are much more complex than these filaments and are designed (for birds of the air) for flight. Each creature was adapted to its environment; that shows design, not evolution. Anyone thinking the dino-bird advocates have scored yardage with this find should read this description of the difference between scales and feathers by Dr. David Menton, and also read our previous reports on problems the Darwin Party wrestles with in their own just-so stories of the evolution of feathers (see 10/30/2003 and 08/21/2001 headlines).