Literature

Although the BAD group (Birds Are Dinosaurs) are in the ascendancy, the small BAND (Birds Are Not Dinosaurs) of dissidents has many reasons to think that currently it has the better arguments. The latest broadside has come from Professor Lingham-Soliar, who has spent a lot of time researching the processes of decay of modern-day organisms in order to better understand partial decay of fossilised animals.

Psittacosaurus without the fuzz

The latest research concerns the skin of the dinosaur Psittacosaurus, a bipedal, plant-eating, ceratopsian dinosaur. This fossil material provides "a deep cross section through the dermis, which includes multiple layers of collagenous fibres in excess of 25, among the highest recorded in vertebrates, with a further 15 more layers (poorly preserved) estimated for the entire height of the section." This is a remarkable find and, as the author writes, it gives us an "unprecedented understanding of the dinosaur skin". The animal was very well protected by this covering:

"These fibre layers comprise regularly disposed fibres arranged in left- and right-handed geodesic helices, matching the pattern at the surface and reasonably inferred for the entire section. As noted from the studies on modern-day animals, this fibre structure plays a critical part in the stresses and strains the skin may be subjected to and is ideally suited to providing support and protection."

Now, Psittacosaurus was a ceratopsian dinosaur "occupying a phylogenetic position far removed from theropod dinosaurs and bird origins". Nevertheless, some have suggested that the bristle-like structures adorning the tail of Psittacosaurus were prototype feathers. Lingham-Soliar considers it significant that no traces of protofeathers could be found in the skin. The structures interpreted by others as protofeathers are actually post-mortem collagen degeneration features. Also, he makes a link between this fossil and the therapods:

"How would the dermis of a theropod dinosaur compare structurally with that of Psittacosaurus? Notwithstanding probable differences in thickness, it is reasonable to think that there would not have been fundamental differences in structure between the dermis of a theropod and that of a non-theropod dinosaur in so far as protection and support are concerned."

A report in The Daily Telegraph quotes the author at some length.

"Scientists must really now choose - belief in the nebulous idea of protofeathers or the reality of collagen, the dominant protein in vertebrates. I am convinced from the nonsense spouted by many of the people who denounce collagen in favour of protofeathers that they have never actually seen collagen in its natural or decomposing state."
[snip]
"What is highly significant in the present study are the masses of collagen fibres found - over 40 dermal layers seen for the first time in a fossil animal, which shows how vitally important collagen was in providing support and protection of the enclosed body mass of dinosaurs per se. It is hardly surprising that the Chinese dinosaurs, as they decomposed, exposed quantities of these structures."

This new work is not an isolated finding, but it builds on a substantial body of published research (e.g. Feduccia et al. 2005) showing that the popular theropod dinosaur to bird transformation really is a BAD theory.

A unique cross section through the skin of the dinosaur Psittacosaurus from China showing a complex fibre architecture
Theagarten Lingham-Soliar
Proceedings of the Royal Society B, FirstCite Early Online Publishing; DOI: 10.1098/rspb.2007.1342.

Abstract: This paper reports on a unique preservation of soft tissues in the ventrolateral region of the plant-eating dinosaur Psittacosaurus from the Jehol biota of China. The preservation is of a deep cross section through the dermis, which includes multiple layers of collagenous fibres in excess of 25, among the highest recorded in vertebrates, with a further 15 more layers (poorly preserved) estimated for the entire height of the section. Also, for the first time in a dinosaur two fibre layers parallel to the skin surface are preserved deep within the dermis at the base of the cross section. These fibre layers comprise regularly disposed fibres arranged in left- and right-handed geodesic helices, matching the pattern at the surface and reasonably inferred for the entire section. As noted from the studies on modern-day animals, this fibre structure plays a critical part in the stresses and strains the skin may be subjected to and is ideally suited to providing support and protection. Psittacosaurus gives a remarkable, unprecedented understanding of the dinosaur skin.

See also:

Feduccia, A., Lingham-Soliar , T. and Hinchliffe, J.R. Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence, Journal of Morphology, November 2005, 266(2): 125-66.

Highfield, R. Bald truth about dinosaur feathers, The Daily Telegraph: 09/01/2008