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Fossils found in Siberia suggest all dinosaurs had feathers
The first ever example of a plant-eating dinosaur with feathers and scales has
been discovered in Russia. Previously only flesh-eating dinosaurs were
known to have had feathers so this new find indicates that all dinosaurs could
have been feathered.
The new dinosaur, named Kulindadromeus zabaikalicus as it comes from
a site called Kulinda on the banks of the Olov River in Siberia, is described in
a paper published today in Science.
Kulindadromeus shows reptile-like scales on its tail and shins, and short
bristles on its head and back. The most astonishing discovery, however, is
that it also has complex, compound feathers associated with its arms and legs.
Birds arose from dinosaurs over 150 million years ago so it was no
surprise when dinosaurs with feathers were found in China in 1996. But all
those feathered dinosaurs were theropods, flesh-eating dinosaurs that include
the direct ancestors of birds.
Lead author Dr Pascal Godefroit from the Royal Belgian Institute of
Natural Sciences (RBINS) in Brussels said: "I was really amazed when I saw
this. We knew that some of the plant-eating ornithischian dinosaurs had
simple bristles, and we couldn’t be sure whether these were the same kinds of
structures as bird and theropod feathers. Our new find clinches it: all
dinosaurs had feathers, or at least the potential to sprout feathers."
The Kulinda site was found in summer 2010 by Sofia Sinitsa and her
team from the Institute of Natural Resources, Ecology and Cryology SB RAS
in Chita, Russia. Over several summer digs, the Russian-Belgian team
excavated many dinosaur fossils, as well as plant and insect fossils.
The feathers were studied by Dr Maria McNamara and Professor
Michael Benton of the University of Bristol, who has also worked on the
feathers of Chinese dinosaurs.
Dr McNamara said: "These feathers are really very well preserved. We
can see each filament and how they are joined together at the base, making a
compound structure of six or seven filaments, each up to 15mm long."
Feather expert, Danielle Dhouailly from the Université Joseph Fourier
in La Tronche, France said: "The feathers look like down feathers from some
modern chickens. When we compare them with the leg scales, it looks as if
the scales are aborted feathers, an idea that has been suggested to explain why
modern birds also have scaly bare legs."
Kulindadromeus was a small plant-eater, only about 1m long. It had
long hind legs and short arms, with five strong fingers. Its snout was short,
and its teeth show clear adaptations to plant eating. In evolutionary terms, it
sits low in the evolutionary tree of ornithischian dinosaurs. There are six
skulls and several hundred bones of this new dinosaur at the Kulinda locality.
This discovery suggests that feather-like structures were likely
widespread in dinosaurs, possibly even in the earliest members of the group.
Feathers probably arose during the Triassic, more than 220 million years ago,
for purposes of insulation and signalling, and were only later co-opted for
flight. Smaller dinosaurs were probably covered in feathers, mostly with
colourful patterns, and feathers may have been lost as dinosaurs grew up and
became larger.
ENDS
Notes to editors
Paper
‘A Jurassic ornithischian dinosaur from Siberia with both feather-like
structures and scales’ by Pascal Godefroit, Sofia M. Sinitsa, Danielle
Dhouailly, Yuri L. Bolotsky, Alexander V. Sizov, Maria E. McNamara,
Michael J. Benton, and Paul Spagna, in Science (25th July, 2014).
Images
Copyright movie showing the dig site:
https://www.dropbox.com/s/fn0hhslgvg0khjw/selection%20Kunlinda2.mov
Issued by the Public Relations Office, Communications Division, University of
Bristol, tel: (0117) 928 8896, email: hannah.johnson@bristol.ac.uk
Key questions
How do we know how old the dinosaurs are?
The Kulinda locality is Middle to Late Jurassic in age, about 169-144 million
years ago, and probably in the older part of this range, say from 169-150
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million years ago. Its age is established from regional mapping in Siberia and
from preliminary K/Ar dating. The Kulinda locality rocks belong to the lower
part of the Ukureyksaya Formation, which covers larger areas around
Kulinda, and this geological formation (body of rocks with a certain thickness
and geographic extent) is dated from associated plant and insect fossils which
can be compared, and correlated, with fossils from other places to give the
age. More exact study is needed, and perhaps some radiometric dates from
associated volcanic rocks to narrow down the age range more closely.
How does the age of these specimens compare with that of other feathered
dinosaurs?
The Russian feathered dinosaurs are similar in age to some of the feathered
Chinese dinosaurs, such as Anchiornis from the Tiaojishan Formation in NE
China. In fact, neither the Russian nor the Chinese rock formations are really
well dated, and it will take further work by geologists in both China and
Russia to determine the ages of the rocks better, and then to discover whether
the Kulinda or Tiajishan fossils are older.
What environments did they live in?
The Kulinda dinosaur bones are associated with abundant, well preserved
fossils of plants, insect larvae, and freshwater crustaceans that suggest
deposition in a low-energy, likely lacustrine, fresh-water environment.
Probably Kulindadromeus fed on the plants that are found with it, including
conifers, seed ferns, and horsetails. The dinosaur bones are not in the form of
complete skeletons, but the bones have been transported by rivers, but not far,
because some elements are associated, such as bones of an arm or leg, and the
skin, bearing scales and feathers, is close to the relevant bones.
How are the ‘feathers’ preserved?
The feathers and scales are preserved as carbon-rich films on the rock. These
show three types of scales on the lower legs and along the tail, and three types
of feather—like structures. The carbon within the feathers and scales appears
to have survived, and so the fine detail of the scales and feathers is preserved
with high fidelity.
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Why are the feathers preserved?
Normally hair, scales, and feathers disappear during fossilization. This
usually happens very early in the long road from the dead animal to the
fossil. After the dinosaur died, its carcass would have been picked over by
scavengers, including flesh-eating dinosaurs, and perhaps some early
mammals, as well as insects. These might well remove all flesh from the bones
over a week or so. In the case of the Kulinda dinosaurs, their carcasses did not
undergo this scavenging phase, but they were probably washed away by a
river and dumped on a slow-moving stretch, perhaps at a bend in the river.
They were rapidly covered with muddy sand, and, together with plant and
other debris, quickly buried. The mud seems to be still rich in organic matter,
so this suggests that there was not a great deal of oxygen in these riverbottom sediments, and the whole site might have been black and sulphurous,
so inhibiting further decay.
How important is this new locality?
The Kulinda locality opens a new window on ecosystem evolution. Middle
Jurassic terrestrial sites are very rare worldwide, being known mainly from
England and China so far. To find a nearly complete ecosystem, from plants
to dinosaurs, is very exciting, and each group of fossils requires detailed
study. The fossils are also immensely abundant – there are dozens of dinosaur
individuals represented – so a detailed ecosystem reconstruction can be made.
Of course, to find diverse feather types in an ornithischian dinosaur is of key
importance.
How were the specimens discovered?
The site was discovered by Sofia M. Sinitsa, and her team from the Institute of
Natural Resources, Ecology, and Cryology, Siberian Branch of the Russian
Academy of Sciences, while they were conducting a geological survey in the
Olov Depression along the small Kulinda River, close to Chernyshevsk
village, in 2009. Four trenches were opened in the lower part of the
Ukureyskaya Formation, and they found dinosaur bones. Then, they
conducted a further series of excavations nearby in 2010 onwards (during the
summer – winters in Siberia are not a good time for such work). In 2012, they
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invited Dr Pascal Godefroit from the Royal Belgian Institute of Natural
Sciences , a world expert on ornithischian dinosaurs, to be involved.
How common are ornithischians?
Ornithischians represent about half of all dinosaurs, and all of them were
plant-eaters. They include unarmoured, two-legged forms that ranged in
length from 1-10 m, such as Iguanodon and Lambeosaurus. The most abundant
were the hadrosaurs of the Late Cretaceous. Other ornithischians sported
armour of various kinds, such as the stegosaurs, with bony plates and spikes
down their backs and tails, the ankylosaurs, enclosed in a chain mail of
armour plates, the thick-headed pachycephalosaurs, and the ceratopsians,
with bony frills over their necks and horns over their eyes and snouts. There
are 300 or more species of ornithischians so far known, and they have been
found worldwide. Dinosaurs are, however, rare in Russia, with only isolated
finds reported from Siberia before.
What is the key significance of the new find?
The new find proves that all dinosaurs had feathers.
Up to now, feathers have been reported from numerous species of theropod
dinosaurs, the flesh-eating groups, and this has confirmed a remarkable
evolution in feather type and complexity through 50 million years of the Late
Jurassic and Cretaceous. Feathers in theropods had begun as simple bristles
that provided two functions: insulation and signalling (through bright colours
and patterns). They were associated with miniaturization of the advanced
theropods, called Paraves, and their wide experimentation with flight.
‘Feathers’ have been reported before in two ornithischians, Tianyulong and
Psiattacosaurus, but palaeontologists had been cautious about the significance
of these because they appeared to be rather simple quills, and perhaps limited
in extent over the body. Our new find shows that feathers occurred all over
the body in a primitive ornithischian, and that there were three types of
feathers, including branching, down-type feathers.
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For interviews and more information, please contact directly:
Dr. Pascal Godefroit
O.D. Earth & History of Life
Royal Belgian Institute of Natural Sciences
Rue Vautier 29, B-1000
Brussels, Belgium
Pascal.godefroit@naturalsciences.be
00 32 2 627 44 95
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