What is your first thought when
someone mentions the word dinosaur ? Perhaps it is the image of the infamous Diplodocus
skeleton which cannot fail to attract your attention on entering the Natural
History Museum, London. Maybe thanks to Spielberg’ s Jurassic Park it’s the prospect of the dinosaur of your nightmares
the Velociraptor terrorising anything unfortunate enough to cross its path. For
me I suppose it’s a mixture of Spielberg’s master class, many trips to natural
history museums, hours of being glued to text books and in my younger years playing
with many, many toy dinosaurs, rarely a trip out went by without another being
added to the collection. And it was recently reading text on some fascinating
new discoveries in the world of palaeontology which have provided the
inspiration for the core of this latest blog. Such is my passion for the subject
that after this I have decided to include a section dedicated to this field in
every publication following this. As always I hope you enjoy it.
Reign of the dinosaurs.
Dinosaurs first appeared in the form
of Protodinosaurs some 252.3 million years ago after the Permian- Triassic
extinction earlier than previously thought recent research has revealed. Tracks
found in Poland and spreading across three ecosystems and four million years
were discovered close to the village of Stryczowice. The evidence suggests
however that these dinosaurs would of likely been smaller than a domestic cat
with the largest tracks measuring 40 millimeters. Dinosaurs domination of the
planet lasted until the late Cretaceous period 65 million years ago where a
mass extinction event paved the way for mammals to assert themselves and begin
a new reign of domination.
Characteristics of a dinosaur.
· Dinosaurs are divided into two predominant groups,
Saurischian meaning lizard hipped or Ornithischian meaning bird hipped species.
· Erect leg posture as a result of cylindrical
femoral head which fitted into a perforated hip socket and a hinge- jointed
ankle.
·
All
species were hind limb dominant.
·
Tail in most cases held off the ground.
·
Scales present on body which formed a non
overlapping mosaic pattern.
·
Dinosaurs would often reach sexual maturity before
growth had been completed.
http://static.guim.co.uk/sys-images/Guardian/Pix/pictures/2014/3/5/1394062955047/New-dinosaur-species-disc-009.jpg
http://static.guim.co.uk/sys-images/Guardian/Pix/pictures/2014/3/5/1394062955047/New-dinosaur-species-disc-009.jpg
Were dinosaurs warm blooded?
In recent years the preconception of dinosaurs being cold blooded like their
modern day cousins has been thrown into doubt as a growing list of evidence to
the contrary continues to build up.
Dinosaurs it was argued had to have been cold blooded as a result of belonging
to the archosaur group the same group in which their close relative the
crocodile also belongs . Professor Roger Seymour however in his study
Dinosaurs, endothermy and blood pressure, stated that as a result of their long
necks, high blood pressure would have been essential to get blood into their
long necks. He also added that to successfully control the flow of blood a four
chambered heart very much like those found in mammals and birds today would
have been required. Seymour also believes that all archosaurs began as warm blooded
creatures and crocodiles switched to a cold blooded life style as a result of
their sit and wait behaviour.
Counter arguments to the suggestion have included the positioning of
sauropod necks. It has been suggested that if their necks remained horizontal
there would have been little need for high blood pressure to ensure blood
reached the brain.
Inertial homeothermy a system where animals are able to slowly warm up
and cool down it has been suggested could have been employed by dinosaurs. It
has however been counter argued that not all dinosaurs were large and even
large dinosaurs began life small.
Further research from Seymour adds more weight to the warm blooded argument.
In 2011 he compared the nutrient foreman – holes in thigh bones where blood is
supplied to the bone of mammals and modern day reptiles. His hypothesis was the
more active the animal the more blood needed to be supplied. He was proven
correct the holes were indeed larger in mammals. He then compared these to
dinosaur bones and found surprising results. The nutrient foreman found in
dinosaur bones was greater than those found in mammals. This meant dinosaurs must
have had to of had a high metabolic rate. Velociraptor and T.rex add further weight
to this argument with findings revealing they were capable of top speeds of
38km and 29 km per hour respectively.
A team from the Catalan Institute of Palaeontology
have also revealed significant evidence pointing in the direction of dinosaurs being
cold blooded when they discovered lag lines on the bones of mammals. Lag lines
are caused when environmental conditions are not favourable for growth and
energy is instead used for the pure survival of the animal. A similar principle
also occurs in trees. As these marks had been found on both dinosaurs and
modern day reptiles it had been assumed dinosaurs were cold blooded. The
finding of these marks on mammal bones proves this piece of evidence at least
cannot be used to support the cold blooded theory.
And so with the list of evidence in favour of proving
these creatures to be warm blooded, it would seem unless a finding of equal
significance is found to contradict these new revelations, it would seem what
we thought we knew about dinosaurs continues to be thrown into doubt.
Dinosaur vocalisation.
A long trachea would have enabled long necked
dinosaurs it is theorised to transmit low frequency noises over a large
distance. It is also thought the nasal passages
found in the crests of duck billed dinosaurs known as hadrosaurs would
have resonated at low frequencies and as a result may have been able to create
low frequency noises.
The preconception of forests reverberating to the
sounds of dinosaur vocalisation however could well be proven to be inaccurate. Hadrosaurs
for example may have been able to produce low frequency sounds, but scientists
are looking to modern day reptiles for answers to how these sounds could have been
produced without the need for vocal chords. King cobras are shown as an example
for how this could work, they possess soft tissue resonating chambers, capable
of amplifying frequencies and consequently making hisses sound like growls. It
has been suggested hadrosaurs could have also been capable of this.
And further evidence increases the likelihood of the range
of dinosaur vocalisation being limited. Dinosaurs originate from the bird
linage of divergence and so it could have been presumed they would possess the
same vocal characteristics as birds today. This has been proven to be incorrect
however with no evidence of vocal chords in either the earliest birds in the
Mesozoic era or in their dinosaur relatives. Dinosaurs may have developed vocal
chords independently of birds however there is no clear cut evidence of this.
Dr Senter concludes as a result of this evidence that dinosaurs like their
modern day relatives would most likely of hissed when disturbed and would have been
unable to properly vocalise.
Evidence of dinosaur battles.
Therapod dinosaurs due to the predatory lifestyle they
led are likely to be found with evidence of battle wounds. Two Allosaurus
skeletons reveal evidence of the hardships of living a predatory lifestyle. One
was found with injuries too its ribs, tail, shoulder, feet, toes and serious
infections to its foot, finger and a rib. The severity of some of the injuries
observed mean it is possible they were a factor in the predators death. In another
skeleton an Allosaur tail suffered an injury suspected to be caused by the
spike of a stegosaur. A famous Tyrannosaur skeleton named “Sue” revealed
serious injuries caused by conflict with another Tyrannosaur and were found to reveal
evidence of successful healing.
The fossil record also shows evidence of battles where
herbivores successful repelled their attacker. A Triceratops horn was found to
have been bitten off by a tyrannosaur however there was evidence of healing
which would imply a successful outcome for the herbivore. Sauropod and Hadrosaur
remains have also show evidence of healing after encounters with predators. The
spikes of Stegosaurs have been found broken and damaged again with evidence of
healing confirming these would have been used to fight.
Dinosaur facts bullet points.
·
700 species of dinosaur have been found 100 of
those in Britain.
· The largest dinosaur was Argentinosaurus,
measuring in at 37 metres from head to tail, it was the length of a Boeing 737.
It would have needed up to 100,000 calories per day.
· The infamously small arms of Tyrannosaurus Rex
could have either been used for holding prey, or if they had feathers as a
courtship display.
·
The second toe of the Velociraptor was not used
for slicing prey as first thought, instead it was used for gripping and pinning
.
·
It has been theorised the tail of the Diplodocus
may have been used as a weapon.
·
The head crest of Cryolophosaurus had the ability
to flush blood as a result the colour of the crest would change and would have been
used to either warn of danger or sexual availability.
·
The longest carnivorous dinosaur is thought to be Spinosaurus it is estimated it could have reached lengths of up to 18 metres.
New species of dinosaurs are discovered with incredible
frequency, which makes the thought of what is still out there unknown to us
waiting to be found so exciting. Here a new species has within the last few
days been discovered in Venezuela.
Twitter ReallyWildWykes
References
Science Uncovered - Dinosaurs rediscovered
Dinosaurs a Field Guide
http://www.sciencedaily.com/releases/2010/10/101006085311.htm
