Procynosuchus
Name:
Procynosuchus
(Before dog crocodile).
Phonetic: Pro-cy-no-soo-kus.
Named By: Robert Broom - 1938.
Synonyms: Cyrbasiodon, Parathrinaxodon.
Classification: Chordata, Synapsida,
Therapsida, Cynodontia, Procynosuchidae.
Species: P. delahareae, P. rubidgei.
Diet: Piscivore.
Size: 60 centimetres long.
Known locations: Africa, including South Africa
and Zambia. Europe, Germany.
Time period: Late Permian.
Fossil representation: Several specimens.
Although
the name essentially means crocodile, Procynosuchus
was actually a
cynodont descended from mammal like reptiles like the therapsids.
Procynosuchus is not the only mammal like reptile
to cause some
confusion like this as others such as the therapsids Biarmoscuhus
and
Titanosuchus
suggest that they are crocodiles when you glance at the
name, but are actually very different when you see the fossils.
Procynosuchus
is usually depicted as living like an otter because of several features
that suggest Procynosuchus was much better suited
for swimming than
exclusively terrestrial movement. One area in particular is the tail
which is considerably longer than in other cynodonts from the time.
The haemal arches which are on the underside of the tail vertebrae
would have considerably increased the depth of the tail resulting in it
becoming a powerful swimming aid when moved from side to side,
unsurprisingly like a crocodile.
While
the tail may have been the primary method of locomotion, the legs and
feet of Procynosuchus also show special adaptations
for swimming. The
femurs (upper bones of the rear legs) have prominent ridges that
would have served for additional areas of muscle attachment. Stronger
muscle attachment would allow the legs to be either held steady or
actively moved depending upon the required movement. The foot bones
were also quite straight resulting in a flat foot that acted as a
paddle.
The
limbs, feet and associated muscles meant that Procynosuchus
was
perfectly able to swim through the water by using just its legs, or
using its legs for steering while being driven forward by the tail,
and any combination of these two areas in between. Despite these
special aquatic adaptations Procynosuchus was still
perfectly able to
walk about on land with a degree of agility. Something that was vital
when you consider that Procynosuchus would still
have to return to land
to rest and rear young.
These
adaptations would have allowed Procynosuchus to
actively pursue prey
like fish, especially around submerged obstacles and through plants
that would have required agile rather than fast swimming. The teeth
of Procynosuchus were more mammalian than
reptilian, with cusps
(additional points) that projected from the bottom. These cusps
would have provided an extra area for shearing through fish allowing
Procynosuchus to make short work of prey.
All
together these adaptations also indicate that while animals may have a
different genetic heritage, the ecological niches in nature rarely
disappear altogether and often repeat throughout time. This results
in different kinds of animals developing similar body plans and
adaptations, building support for cases of convergent evolution.
Procynosuchus
is actually a name that has defied the standard rules zoological
nomenclature because this name was granted to the genus after two other
names had already been assigned. Broom had named the first material
relating to Procynosuchus earlier in 1931,
however back then he had
named it Cyrbasiodon. Another specimen was named Parathrinaxidon
by
Parrington in 1936, however this name in itself would usually be
treated as a synonym to Cyrbasiodon. Neither of
these two earlier
names however gained widespread use in reference, whereas
Procynosuchus became very common to the point of
general inclusion in
books about prehistoric animals that were marketed towards the general
public and not just specialists. It is for this reason that
Procynosuchus was assigned nomen protectum
(protected name) status
by the ICZN in 2010, and why the older names in this case are now
treated as the synonyms.
A
similar special case was actually made for what is perhaps the most
famous dinosaur of all time, Tyrannosaurus
rex. The very first
Tyrannosaurus material discovered back in 1892
was actually named
Manospondylus gigas. However because Manospondylus
gigas was hardly
ever used even within palaeontological circles and Tyrannosaurus
was so
well known by so many the world over, the ICZN also assigned nomen
protectum status to Tyrannosaurus.
Further reading
- A further contribution to our knowledge of the fossil reptiles of the
Karroo. - Proceedings of the Zoological Society of London
107(3):299-318. - R. Broom - 1937.
- The primitive cynodont Procynosuchus: structure, function and
evolution of the postcranial skeleton. - Philosophical Transactions of
the Royal Society B. 288 (1027): 217–258. - T. S. Kemp - 1980.
- OPINION 2264 (Case 3431) Procynosuchus Broom, 1937 (Therapsida,
Cynodontia): generic name conserved. - Bulletin of Zoological
Nomenclature. 37 (4): 348–349. - ICZN - 2010.
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