Name: Baryonyx
(Heavy claw).
Phonetic: Bah-ree-on-ix.
Named By: Alan Charig & Angela Milner -
1986
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Spinosauridae, Baryonychinae.
Species: B. walkeri (type).
Diet: Carnivore.
Size: Roughly about 9 meters long for the holotype,
though this is of a juvenile, Fully grown adult would have been larger.
Known locations: England, Surrey. Spain.
Portugal. Possibly North Africa.
Time period: Hauterivian to th Barremian of the
Cretaceous.
Fossil representation: Remains of many individuals.
In
1983 a fossil hunter named William Walker discovered a large
fossilised claw in a clay pit. Retrieval of this claw also resulted
in the recovery of associated bones that revealed a new and previously
unknown type of theropod dinosaur. Alan Charig and Angela Milner
described and formerly named the new dinosaur Baryonyx
after the
initially discovered large and heavy claw. The species name B.
walkeri
is in honour of William Walker.
The
key area that made Baryonyx different from previous
discoveries was the
fact that its skull resembled the skull of a crocodile, and not that
of other more classically known dinosaurs like Megalosaurus.
Today
Baryonyx is referred to as a spinosaurid dinosaur,
the group named
after the later and much larger Spinosaurus.
An interesting
association between these two dinosaurs is that while Spinosaurus
was
discovered and named much earlier than Baryonyx in
1912, its skull
was not known until the 1990's. It was partly the discovery of
Baryonyx along with other spinosaurids
that allowed
for this to be
realised and up until this point Spinosaurus's
skull was recreated to
look just like any other carnosaur theropod.
The
current classification of Baryonyx is a little
muddled due to the
recovery of other spinosaurid material that may or may not be the same
as Baryonyx. The first possible synonym is
Suchosaurus, which was
named in 1841 after only the teeth. These teeth are almost
certainly those of a spinosaurid, yet are still slightly different
from those of Baryonyx. To complicate matters
though, Baryonyx
teeth are known to show variations between individuals. Although
Suchosaurus has since been considered a nomen dubium
by some
palaeontologists, its existence has still caused some concern about
the future for Baryonyx. One option could be
to split every
Baryonyx specimen that shows individual tooth
variation into its own
species. The other would be for Suchosaurus to be
declared the senior
synonym of Baryonyx, resulting in all future Baryonyx
specimens to be
referred to Suchosaurus.
The
latter scenario actually happened for the dinosaur Troodon,
which
itself was originally named after only teeth, although in this case
the teeth were very characteristic of the genus. Another option is if
a special case is made for Baryonyx as what
happened with Tyrannosaurus,
where originally Tyrannosaurus was named Manospondylus
gigas
although most people only knew the vastly more popular name of
Tyrannosaurus. This resulted in Tyrannosaurus
being assigned nomen
protectum, or 'protected name' status, meaning that even though
Manospondylus was first, Tyrannosaurus
is the name that will now
always be used to refer to the genus.
The
second synonym possibility is the similar dinosaur Suchomimus
that has
been discovered in Africa. Suchomimus lived at a
later stage in the
Cretaceous and is itself larger than Baryonyx.
However the Baryonyx
holotype is thought to represent an individual that is not fully grown
and it is also not known if Suchomimus itself was
fully grown either.
The skeletons between these two genera are very similar except for the
taller neural spines of the vertebrae that are known in Suchomimus.
While different, it could be that the larger neural spines grew with
age and were not present in Baryonyx because it was
not yet old enough
to grow them when it died. Should it be proven that Suchomimus
is the
same genus as Baryonyx then Suchomimus
would become a junior synonym
which means material for Suchomimus would be
re-labelled to point to
Baryonyx.
The
fact that Baryonyx is so far mostly known from
Southern England and
Northern Spain suggests that it lived around the edges of huge body of
water called Wealden Lake. Back in the Cretaceous this lake submerged
a good portion of Western Europe including most of France and parts of
Southern England. Rivers running into it formed an expanse of river
deltas that would have been the ideal habitat for spinosaurid
carnivores like Baryonyx that seem to have been
specially adapted to
hunt for fish.
Baryonyx
is usually envisioned standing on the edges of these water ways,
perhaps actually in the shallows and staring towards the water looking
for fish. The claws were originally thought to have been used for
swiping into and pulling fish out of the water, however this does not
take into account the very special crocodile-like adaptation of the
skull. If the claws were the primary means of prey capture then
surely Baryonyx would have had a regular carnosaur
type skull? The
skull itself is much longer than it is wide or high and would have
afforded Baryonyx a significant reach into the
water. You can see the
benefits of having long jaws when you see a heron or stork striking for
fish in the water. Later studies associated with Spinosaurus
however,
now suggest that at least some spinosaurid dinosaurs were mostly
aquatic, actually swimming through the water after prey.
Baryonyx
also has the addition of a notch at the end of its jaws created by a
curved recess in the premaxilla, and a rounded protuberance in the
lower jaw that roughly matches the curvature of the above recess.
This feature is commonly seen in crocodiles and helps to increase grip
on struggling and slippery prey like fish. The teeth are also thin
and long and are best suited for gripping and holding prey rather than
shearing and crunching. Detailed analysis of the snout of its larger
relative Spinosaurus has also revealed that the end
of Spinosaurus's
snout had pressure sensitive receptors that could have been capable of
sensing the movements
of fish when it was dipped into the water. As an earlier relative,
Baryonyx may have had a similar even if slightly
less developed method
of sensing prey. The robust claws of Baryonyx
were probably used for
gripping and tearing at prey that was already caught, essentially
doing the job of shearing preys flesh in the absence of specialised
teeth for the purpose.
Baryonyx
is one of the few dinosaurs to reveal an insight into its feeding
habits and preferred prey. Firstly the partially digested remains of
the ancient fish Lepidotes
were found within the stomach area of a
Baryonyx specimen from England. This specimen also
however had the
remains of a young Iguanodon
although it’s not certain if Baryonyx
deliberated hunted smaller dinosaurs as well as fish, or had simply
scavenged the body of an already dead dinosaur. Either scenario is
possible, although the fish hunting specialisations of Baryonyx
may
lean more towards the scavenging hypothesis.
Further reading
- Baryonyx, a remarkable new theropod dinosaur. -
Nature
324(6095):359-361. - A. J. Charig & A. C. Milner - 1986.
- The systematic position of Baryonyx walkeri, in
the light of
Gauthier's reclassification of the Theropoda, by A. J. Charig &
A. C. Milner. In Dinosaur Systematics: Perspectives and Approaches
(Cambridge University Press). K. Carpenter & P. J. Currie -
1990.
- Baryonyx walkeri, a fish-eating dinosaur from the
Wealden of Surrey.
- Bulletin of the Natural History Museum of London 53: 11–70. - A. J.
Charig & A. C. Milner - 1997.
- A new look at Baryonyx walkeri (Charig and
Milner, 1986) based upon a
recent fossil find from the Wealden. - Symposium of Vertebrate
Palaeontology and Comparative Anatomy. - S. Hutt & P. Newbery -
2004.
- The spinosaurid dinosaur Baryonyx (Saurischia,
Theropoda) in the
Early Cretaceous of Portugal. - Geological Magazine 144 (6): 1021–1025.
- E. Buffetaut - 2007.
- Functional morphology of spinosaur 'crocodile-mimic' dinosaurs. -
Journal of Vertebrate Paleontology 27 (4): 892–901. - E. J. Rayfield,
A. C. Milner, V. B. Xuan & P. G. Young - 2007.
- A new specimen of the theropod dinosaur Baryonyx
from the early
Cretaceous of Portugal and taxonomic validity of Suchosaurus. - Zootaxa
2827: 54–68. - O. Mateus, R. Ara�jo, C. Nat�rio & R.
Castanhinha - 2011.
-
New spinosaurid dinosaur finds from the Wessex Formation (Wealden
Group, Early Cretaceous) of the Isle of Wight. - SVPCA. 65. - M. C.
Hunt, G. Blackwell, J. Clark & B. Foster - 2017.
- Subaqueous foraging among carnivorous dinosaurs. - Nature. 603
(7903): 852–857. - Matteo Fabbri, Guillermo Naval�n, Roger B. J.
Benson, Diego Pol, Jingmai O’Connor, Bhart-Anjan S. Bhullar, Gregory M.
Erickson, Mark A. Norell, Andrew Orkney, Matthew C. Lamanna, Samir
Zouhri, Justine Becker, Amanda Emke, Cristiano Dal Sasso, Gabriele
Bindellini, Simone Maganuco, Marco Auditore & Nizar Ibrahim - 2022