Cartorhynchus
Name:
Cartorhynchus
(short snout).
Phonetic: Car-to-rin-kus.
Named By: Ryosuke Motani, Da-Yong Jiang,
Guan-Bao Chen, Andrea Tintori, Olivier Rieppel, Cheng Ji
& Jian-Dong Huang - 2015.
Classification: Chordata, Reptilia,
Ichthyosauromorpha, Ichthyosauriformes.
Species: C. lenticarpus
(type).
Diet: Carnivore/Piscivore.
Size: About 40 centimetres long.
Known locations: China.
Time period: Olenikian of the Triassic.
Fossil representation: Almost complete individual.
Cartorhynchus
might well be one of the more ground breaking discoveries regarding
ichthyosaur
research. For over one hundred and fifty years the
origins of the ichthyosaurs have been murky to say the least. We know
that the ichthyosaurs began appearing in large numbers in the
Triassic, so their origin is at least that old. In 2011 a new
kind of aquatic reptile was discovered and later in 2014 a
description of this animal was put forward. Named Cartorhynchus,
this reptile may be an actual ancestor of the ichthyosaurs, or at
least a representative of the reptiles that would eventually give rise
to the ichthyosaurs.
Cartorhynchus
was only about fifty centimetres long, but the tail had already
become flattened to provide greater push as Cartorhynchus
swam through
the water. The limbs had already formed rudimentary paddle structures
and the rear limbs were reduced in size. The eyes were large to
enable better light gathering ability when in the water. The bones
were also thickened to provide greater buoyancy when swimming in the
water, and reduce the effort necessary to swim beneath the surface.
Cartorhynchus
lived during the earliest stage of the Triassic, which is where you
might expect an ancestor for a group of Triassic reptiles to be.
However Cartorhynchus is just one genus, at the
time of writing is
only known from one specimen, and future discoveries may see the
ancestry of the ichthyosaurs go back to the Permian. Though with that
said the Permian/Triassic boundary does mark the biggest extinction
event in the known history of planet (bigger even than the KT
extinction that ended the dinosaurs), so it may be this extinction
that kick started the development of the ichthyosaurs.
If
Cartorhynchus is an example of an early ichthyosaur then that makes it
all the more remarkable that by the late Triassic giant ichthyosaurs
such as Shonisaurus
and Shastasaurus
were swimming in the oceans.
Further reading
- A basal ichthyosauriform with a short snout from the Lower Triassic
of China. - Nature - Ryosuke Motani, Da-Yong Jiang,
Guan-Bao Chen, Andrea Tintori, Olivier Rieppel, Cheng Ji
& Jian-Dong Huang - 2015.
- Repeated evolution of durophagy during ichthyosaur radiation after
mass extinction indicated by hidden dentition" -Scientific Reports. 10
(1): 7798. - Jian-dong Huang, Ryosuke Motani, Da-yong Jiang, Xin-xin
Ren, Andrea Tintori, Olivier Rieppel, Min Zhou, Yuan-chao Hu &
Rong Zhang - 2020.
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