A mummified fossil of Edmontosaurus regalis has been found to have a crest on its head.
Phil Bell, a paleontologist at the University of New England, Australia,
discovered the soft-tissue crest on the hadrosaurid (duck-billed dinosaur)
fossil while studying it. The discovery of the fleshy crest on this fossil from
the Wapiti formation in Alberta, Canada was so unexpected, Bell put his chisel
straight through the structure. Many hadrosaurids have been previously
described to have bony crests, but CT scans showed the crest on this fossil had
no osseous (bony) support, similar to a rooster’s comb. This is the first
dinosaur fossil to be found with a fleshy crest.
Without an underlying bone
support or air passages, the most probable use for the crest was for
socio-sexual display. Comparing it with the fleshy combs of present-day roosters,
grouse and condors, Bell theorized that the crest might have served the same
function: to indicate the strength and fertility of the male. Given also the
knowledge that Edmontosaurus was a
herding animal, the crest may have also indicated the top male within a herd,
he said.
Aside from the discovery of the
soft-tissue crest, the fossil was interesting also for having very
well-preserved skin. "For the skin to preserve, these animals had to be
buried very rapidly, probably within a day or two after they died, and the
chemical environment in the sediment was just right," Bell said.
Bell speculates the loss of the
bony crest of the hadrosaurids’ ancestors and the substitution of the fleshy display
structure in Edmontosaurus through
evolutionary processes. Creation scientists, who believe in a literal 6-day creation
of the universe, point out that these speculations based on evolutionary
assumptions are just that: speculations. "The actual bones of Edmontosaurus have absolutely no
indication that there's a crest of any sort in this animal, so similar crests
or other fleshy structures could have been really widespread among
dinosaurs," Bell said. It is then possible that other dinosaurs may have
also possessed fleshy crests but simply failed to fossilize and be preserved. Thus,
creation scientists point out, guesses on the evolutionary development of the
fleshy crest in this dinosaur’s lineage remains speculative since the fossil
evidence does not necessarily support them. Though Bell and his colleagues
write, “The discovery of a fleshy crest in Edmontosaurus regalis reveals
that some later hadrosaurines did not in fact lose their ornamentation but
evolved an alternative solution to the bony crests that were widespread within
the clade”, creation scientists point out that “the discovery of the fleshy
crest ‘reveals’ no such thing.”
Creation scientists believe that
the rapid burial conditions required by such well-preserved specimens were
provided by the worldwide flood of Noah’s day. The “undulating and partly wrinkled” skin of the
specimen’s neck seems to have resulted from the head of the specimen having
arched sharply backward. This and other features consisting of the mouth open
and the tail arched upward are part of a characteristic death pose that is so
frequent among dinosaur fossils, it has been given a name: the opisthotonic
death posture. Research has suggested
that this death posture is associated with immersion in water. “The violent
rising waters of the global Flood would have provided the loads of sediment
needed to catastrophically bury billions of animals and plants, triggering opisthotonus in
dying dinosaurs and ultimately providing the conditions that preserved many as
fossils”, creation scientists claim.
The fossil specimen shows the
first ever discovered fleshy crest in a dinosaur fossil. Since there were no evidence
of this on its bones, it is absolutely possible for other dinosaurs to have
this fleshy structure without revealing it in their fossils. While it is definitely
possible for Edmontosaurus to have
used this structure for visual socio-sexual display, this behavior does not fossilize;
thus this speculation on the structure’s function cannot be conclusively proven
with the current fossil evidence. Nor does the fossil evidence show how the
structure evolved in the dinosaur’s lineage. Whether the reader holds to
evolutionary or biblical assumptions, it is important to discern between what
can be clearly observed and which are unsupported speculations.
References:
http://news.nationalgeographic.com/news/2013/12/131212-duckbill-dinosaur-rooster-comb-fossils-paleontology-science/
http://www.answersingenesis.org/articles/2014/01/02/dinosaur-crest
Categories: