This is a recent revelation and
an important one. There is still little
hope of recovering DNA yet one can not think of a better place to look and we
have had recovery from dinosaur fossils claimed. It is a good start to recognize a dinosaur
feather.
It strikes me that extensive feathered
lined nests existed among the resin producing trees and that such locations
were ideal for this type of fossil production.
Certainly it helps make DNA
recovery a little more plausible and may help generate pertinent data in time.
Perfectly preserved dinosaur feathers found in southern Alberta
Perfectly preserved dinosaur feathers were found in southern Alberta
Updated: Fri Sep. 16 2011 12:01:24
ctvedmonton.ca
A unique discovery has been made in southern Alberta
The first prehistoric feathers were found perfectly preserved in amber
uncovered in southern Alberta
This marks the first time such a sample has been found -- a real change
for experts who are used to studying feathers fossilized in rock.
"It's a kind of preservation that can have a lot of detail, but in
amber what you have essentially is the original feathers and they're preserved
in three dimensional detail," said Dr. Philip Currie, with the University
of Alberta.
Currie said researchers at the University of Alberta will be able to
study the feathers in more detail than before, since they are so well-preserved
and can even see colour.
Dinosaur Feathers Found in Amber Reinforce Evolution Theories
SEP 15 2011, 10:40 AM ET12
Protofeather fossils discovered entombed in amber from the Late
Cretaceous era support theories of dinosaur and avian evolution -- and make for
one beautiful gallery
Dinosaur and bird feathers preserved in amber from a Late Cretaceous
site in Canada reveal new insights into the structure, function, and color of
animals that date back to about 78 million years ago.
Researchers led by University
of Alberta
In the gallery below, with captions from McKellar, marvel at the beauty
of these amber-preserved feathers. Then, in the Q&A that follows, learn
more about how amber preservation works, the science of feather evolution, and
the possibility of Jurassic Park-type experiments down the line.
A feather barb trapped within a spider’s web in Late Cretaceous Canadian
amber. This barb displays microscopic features that indicate it was once part
of a vaned feather and was likely borne by a flying bird. This particular
specimen began our search for additional feather inclusions in the amber
deposit.
How significant is this discovery?
This discovery is a pretty significant find. It supports a model for
the evolution of feathers that has previously relied on compression fossils
that are difficult to interpret and have been hotly debated.
Also, the amber-entombed feathers show that some of the most primitive
feather types, also known as protofeathers, were still around just before the
dinosaurs went extinct. They existed alongside feathers that are nearly
identical to those of modern birds. Given what we know about the animals that
were alive in the area at the time, it is reasonable to suggest that the
protofeather-like specimens are attributable to dinosaurs and are the first
specimens of this type of feather to be recovered from amber.
How does amber preservation work exactly?
Preservation in amber can vary quite a bit among deposits. Amber tends
to preserve specimens in great detail because tree resin has antibacterial and
drying properties that partially mummify inclusions and slow the initial
onslaught of decay. Over many years, the resin polymerizes, turning into a
plastic-like substance that is quite resilient, but burial usually results in
heating that can have a profound effect on the inclusions over the span of
millions of years.
The Canadian amber insect inclusions are largely preserved as hollow
voids in the amber, with a thin film of carbonized, coal-like material, where
the outside of the insect once was. The feathers appear to have fared much
better, because they are fine and are not composed of material that decay
easily. That said, many of the specimens show signs of partial decay, and there
is no indication of how much, if any, original material remains intact.
What's the backstory of these specimens?
What originally got me interested in this project was a single feather
fragment trapped in a spider web that had been given to Dr. Brian Chatterton.
For my Ph.D. project, I worked on tiny, less than three millimeter, parasitic
wasps trapped within amber from the same deposit. As part of this project I was
able to go through the Royal
Tyrrell Museum Alberta ,
who donated a pair of additional specimens to the University of Alberta
This project underlines the importance of maintaining museum
collections as well as the role that interested amateurs can play in
palaeontology. Without these, there is no way that we would have been able to
observe these important specimens.
According to your paper, these feathers represent several distinct
stages of feather evolution. Could you explain each stage briefly?
The evolutionary-developmental model is an attempt to explain how the
transition from small hair-like feathers to modern feathers with multiple tiers
of branching occurred. A quick account of modern feather anatomy would go like
this: Feathers have a central shaft called the rachis. Off of this shaft branch
the tufts, which in turn branch off into small structures called barbules that
are segmented like bamboo shoots.
Stage 1 consists of individual filaments that are comparable to hair in
terms of overall appearance. Stage 2 consists of multiple filaments that arise
from a single base, forming barbs. Stage 3 is where feathers become branched
structures, either by forming segmented barbules on their barbs or by forming
barbs on their central shaft, the rachis, and then combining these features to
make two tiers of branching. Stage 4 is where the barbules on each side of the
barb were altered to connect barbs together and form a sheet or vaned feather.
Stage 5 encompasses a wide range of finer alterations that actually permit
powered flight and a wide range of additional uses for feathers.
The notion of dinosaur specimens preserved in amber reminds me of Jurassic Park
Would what happened in that movie be plausible? What can we look
forward to learning?
Put simply, no. The specimens that we examined are extremely small and
would not be expected to contain any DNA material. To put this into context,
the only genetic material that has been recovered from amber is from lumps of
mummified insect muscle tissue in much younger Dominican amber that are
approximately 17 million years old and well after the age of dinosaurs.
If we are able to obtain more material, we would really like to examine
the chemical makeup of the protofeather-like specimens, as well as the pigments
found within these specimens and other feathers. It would then be possible to
investigate how much of the original feather material remains intact and gain a
better understanding of the feathers' colors.
Unfortunately, these investigations rely on being able to create small
breaks within some of the specimens and examine them under very high
magnifications, such as scanning electron microscopy, so they are not possible
with the limited number of specimens that are currently available. A larger
collection may also allow us to verify some of the other stages in feather
evolution.
No comments:
Post a Comment