Science Literature

The new find "will either be nothing or the biggest revolution in paleontology ever". These words were spoken by a palaeontologist in response to newly published research. He was commenting on a report of well-preserved tissues and primary collagen sequences recovered from the femur of a plant-eating dinosaur identified as a hadrosaur. It followed several years of intense activity by Mary Schweitzer and colleagues, whose previous papers on soft tissues in dinosaur bones were met with great scepticism. Last year, it seemed as if the claim had met its final rebuttal when the soft tissues were suggested by the same palaeontologist quoted above to "have come from bacterial contamination". However, the new research appears to have answered the critics very effectively.

Multiple hadrosaur red blood "cells" surrounded by white, fibrous matrix (Credit Mary H. Schweitzer, Source here)

The authors were well aware that their newly reported work adds fuel to the fire of controversy. They start their abstract by reminding readers about it and they end their paper with comments addressing the "appropriate skepticism" of earlier work. The problem is this: all direct measurements of the degeneration of biomolecules suggest timescales of hundreds or thousands of years (depending on environmental conditions). Indirect measurements, based on detecting biomolecules in artefacts of known age, suggest that the upper limit is less than a million years. Yet, the biomolecules detected in dinosaurs are considered to be 80 million years old. Two orders of magnitude justifies considerable skepticism!

Consequently, the authors have gone to great lengths to address concerns of contamination - particularly by the invasion of bacteria to form biofilms. The femur they have used came from an articulated hindlimb of a hadrosaur. The pes elements, tibia and fibula were collected in 2006, so they knew the femur was still embedded in rock. The following year, the rock containing the femur was removed, taking care that the fossil bone "was not exposed in the field". Every effort was made to prevent contamination so that all the materials examined were representative of the fossil itself. The researchers found a variety of morphological evidences that indicated they were handling fossil material of significance. "The variation in texture, microstructure, and colour of dinosaur material is consistent with extant tissues and not plausibly explained by biofilms". A battery of tests followed, with replication by another lab, leasing to some very convincing findings. Many critics of the earlier work are acknowledging the substantial nature of the new research. Service writes:

"Both groups then independently performed biochemical and antibody-binding studies that showed evidence of collagen as well as laminin and elastin, two proteins found in blood vessels."
[McIntosh, a critic of the earlier work, is quoted as saying:] "I'm not saying it's true. But I cannot right now make a plausible argument that it's not true." He adds: "The door is closing on plausible alternatives."

Yet another aspect of the newly published research is a comparison of the hadrosaur collagen sequences with collagen from birds, reptiles, mammals, amphibians and with the previous sequences obtained for T. rex. The findings from this comparison have captured headlines across the world. The emerging phylogenetic tree first places the two dinosaurs adjacent to the birds - subsequent to the branching point with reptiles. Undoubtedly, both dinosaur sequences are fragmentary. "The eight peptide sequences for collagen alpha1 type I and collagen alpha2 type I represent 7.8 and 2.5% of the full-length sequence for related organiosms, respectively." Nevertheless, whilst acknowledging this, the authors regard their analysis as a significant output.

"The amount of missing data in B. canadensis and T. rex sequences relative to extant samples resulted in relatively low resolution within Dinosauria, but even so, the phylogenetic relationship of recovered B. canadensis sequences supports the species' placement within Archosauria, closer to birds than Alligator."

In view of this, the sequence comparisons can and will be critiqued. Comment at this stage may be premature (although go here for further thoughts on the matter). From a design perspective, there is another angle on sequence comparisons worth considering. Instead of interpreting sequences in terms of evolutionary pathways, with similarities mapping ancestor/descendant relationships, similar sequences may actually correlate with similar functionalities. So, for example, similarities between dinosaur and avian collagen may result from similar design requirements relating to size/weight/strength criteria. These similarities are not evidences for birds and dinosaurs belonging to the same clade, but they are evidences for birds and dinosaurs having common physiological and anatomical design features.

One further point relates to the 'god-of-the-gaps' style of argumentation. ID scientists are unfairly charged with finding a gap in knowledge and filling it with a miracle (whereas design arguments are actually based on evidence - not the lack of it). With dinosaur soft tissue preservation, the shoe is on the other foot. All the knowledge we have points to the impossibility of detecting any protein sequences from dinosaurs. On these grounds, many were intensely sceptical of the T. rex analysis. Now that collagen sequences have been confirmed by replication, the challenge is to explain what was previously considered impossible. The authors conclude their paper with the words: "still unknown is the chemistry behind such preservation". On the basis of what we know, the creationist claim that the dinosaurs are not millions of years old might seem the more parsimonious. The point I am making is that 'god-of-the-gaps' charges are misdirected whenever people argue from evidence, and that most instances of the use of the phrase reveal its role as a rhetorical tool.

Biomolecular Characterization and Protein Sequences of the Campanian Hadrosaur B. canadensis
Mary H. Schweitzer, et al.
Science, 324, 1 May 2009: 626-631.

Abstract: Molecular preservation in non-avian dinosaurs is controversial. We present multiple lines of evidence that endogenous proteinaceous material is preserved in bone fragments and soft tissues from an 80-million-year-old Campanian hadrosaur, Brachylophosaurus canadensis [Museum of the Rockies (MOR) 2598]. Microstructural and immunological data are consistent with preservation of multiple bone matrix and vessel proteins, and phylogenetic analyses of Brachylophosaurus collagen sequenced by mass spectrometry robustly support the bird-dinosaur clade, consistent with an endogenous source for these collagen peptides. These data complement earlier results from Tyrannosaurus rex (MOR 1125) and confirm that molecular preservation in Cretaceous dinosaurs is not a unique event.

See also:

Service, R.F. 'Protein' in 80-Million-Year-Old Fossil Bolsters Controversial T. rex Claim, Science 324, 1 May 2009: 578.

New Data from 80-Million-Year-Old Dinosaur Demonstrates Ancient Protein Is Preserved, Beth Israel Deaconess Medical Center Press Release, 30 April 2009.

Tyler, D. T. rex - spectacular findings - wrong message. ARN Literature Blog (29 April 2008)