may have knocked Archaeopteryx off
the perch --so to speak - as being the
earliest bird, a title for which there
are now many contenders. The dis-
covery of Archaeornithura in 2015
dates ‘true’ birds as having arisen a
little over 130 million years ago.
filaments that projected a few
millimetres above its skin, suggesting
an insulating and possibly thermo-
regulatory function. This contrasts
with another coelurosaurian therapod
that also existed approximately 130
million years ago. Beipiaosaurus only
measured 2m in total body length, but
boasted integumentary filaments up
to 150mm long. Their structure
(single and broad – up to 2mm wide)
came in a great range of hues. The
fact that Late Jurassic and Early
Cretaceous dinosaurs with pinnate
feathers exhibited sexual dimorphism
in plumage and colour patterning
likewise presents a strong case that
mate attraction and display functions
were a key role for these more
advanced feather types.
But the evolution of filamentous
‘protofeathers’ preceded powered,
feathered flight by at least 100
The limitation of fossils of carbon-
million years. Based on
ized impressions is
fossil evidence, the first
that although they
feathers, in the form of
indicate the presence
SEXUAL
simple, fibrous, single
of feathers, they are
filaments, had evolved
often poorly
DIMORPHISM
PLUMAGE
in non-avian theropods
resolved; in contrast,
by 190 million years
specimens preserved
COLOUR PATTERNING
ago. These were by no
in amber (despite
means suited to flight,
being extremely rare)
and are most likely to have been used and localised distribution on the head, exhibit extremely fine structural
neck and tail means they would
for thermoregulation and display,
detail. Amber-preserved feathers
function poorly as insulation, but
although a variety of other possible
from the Late Cretaceous reveal the
would be well suited for display.
functions include crypsis, tactile-
evolution of a great diversity of
Analysis of the melanosomes
sensation, physical defence, water-
feather types, which were likely to
(pigment-containing cells) of fossil
repellency, communication, and
have served a range of functions in
dinosaur feathers reveal that feathers avian and non-avian dinosaurs. Many
species or mate recognition or
were not uniform in colour, but rather feathered dinosaurs retained scales,
selection. Feathers function as an
incredibly good insulating
body cover, which is very
important in aiding modern
birds to maintain a high body
temperature, driven by the
high metabolic rate necessary
for powered flight. They can
help regulate body tempera-
ture and prevent overheating
by being raised and lowered
to alter the amount of insula-
tion, and can shed excess
heat through the blood that
flows through their vanes.
‘Late Jurassic and Early Cretaceous
dinosaurs exhibited
in
and
.’
Sinosauropteryx prima is
known from a fossil dated at
about 130 million years ago,
and was a small, lightly-built
coelurosaur with relatively
long legs and tail. It was
covered with tufts of thick
Above left: Archaeopteryx
has for a long time been
considered the ‘first bird’.
Image by Catmando.
Below left: this depiction of a
Velociraptor is at odds with
the traditional view of
dinosaurs. Image by Linda
Bucklin.
Right: Beipiaosaurus boasted
integumentary filaments up to
150mm long. Image by
Catmando.