Cretolamna
occasionally spelled as Cretalamna
Name:
Cretolamna
(Cretaceous Lamna).
Phonetic: Cree-toe-lam-nah.
Named By: Glikman - 1958.
Synonyms: Lamna appendiculata, Lamna
appendiculatus, Otodus appendiculatus.
Classification: Chordata, Chondrichthyes,
Elasmobranchii, Selachimorpha, Lamniformes.
Species: C. appendiculata, C.
appendiculata appendiculata, C. appendiculata pachyrhiza, C.
aschersoni, C. biauriculata, C. gunsoni, C. lata, C.
maroccana, C. pachyrhiza.
Diet: Carnivore/Piscivore.
Size: Average length seems to have been anywhere
between 2 to 3 meters, though rare examples indicate an upper
size approaching 3.6 meters long.
Known locations: Fossils are literally known in age
appropriate marine deposits worldwide.
Time period: Roughly Barremian of the Cretaceous to
the Mid Miocene.
Fossil representation: Mostly teeth and vertebrae.
Although
the Cretolamna shark
genus is extinct today,
there is no doubt that
it was one of the most successful of all shark genera. Fossils of
Cretolamna (mostly of teeth and vertebrae) are
known from all over
the world and range from the early Cretaceous to the mid Miocene in
age, making Cretolamna one of the most widely
distributed shark
genera in not just geographical range but throughout time as well.
Only a few other shark genera such as Hybodus
can claim to rival this
success. Because the first fossils of Cretolamna
were found in
Cretaceous aged deposits, the genus was given a name which means
‘Cretaceous Lamna’, with the Lamna part referencing the similarity
to the Lamna shark genus, which is the type genus
of the Lamniformes
group of sharks (The group that includes many modern kinds such as
the great white, thresher shark, porbeagle, mako, etc).
Cretolamna
would have looked much like modern day lamniform sharks, and likely
would have been a pelagic (open water) predator of other fish.
However, Cretolamna living before the KT
extinction during the
Cretaceous and would have had the option to hunt marine reptiles such
as plesiosaurs
and smaller mosasaurs,
while those living after the KT
extinction may have attacked primitive cetaceans,
many of which were
much smaller than those we know today. The teeth of Cretolamna
are
broad with cusps at the base of the main crown, indicating that
Cretolamna was best suited to attacking larger prey.
It
is hard to be certain about exactly which different evolutionary lines
that different sharks evolved from. However in the past the
Cretolamna genus has been speculated to be the
origin of other large
predatory sharks, including the genera Otodus,
and
Paleocarcharodon.
Paleocarcharodon is regarded as
a possible ancestor
to Carcharodon carcharias, today better known as
the great white
shark, and largest predatory shark alive today (basking and whale
sharks are larger but these are filter feeders). Otodus
however may
have been the progenitor of the Carcharocles genus
which includes such
behemoths as C.
angustidens, C.
auriculatus, C.
chubutensis,
and largest of all, C.
megalodon.
Cardabiodon, Cretolamna, Cretoxyrhina, Hybodus, Ptychodus, Scapanorhynchus, Squalicorax.
Further reading
- Skeletal and dental anatomy of lamniform shark, Cretalamna
appendiculata, from Upper Cretaceous Niobrara Chalk of
Kansas -
Journal of Vertebrate Paleontology vol 27, Issue 3 - Kenshu
Shimada - 2007.
- Late Cretaceous (Cenomanian-Campanian) mid-palaeolatitude
sharks of Cretalamna appendiculata type - Acta
Palaeontologica
Polonica. - Mikael Siverson, Johan Lindgren, Michael G.
Newbrey, Peter Cederström & Todd D. Cook - 2013.
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