Parapuzosia
Name:
Parapuzosia(near Puzosia).
Phonetic: Pah-rah-pu-zo-se-ah.
Named By: Nowak - 1913.
Synonyms: Pachydiscus seppenradensis.
Classification: Mollusca, Cephalopoda,
Ammonoidea, Desmoceratidae.
Species: P. seppenradensis
(type), P. boesei, P. bradyi.
Diet: Carnivore.
Size: Shell of P. bradyi up to
around 1.8
meters across at the widest diameter. Largest fossil shell of P.
seppenradensis is 1.8 meters at widest diameter, but
this
specimen is incomplete. Estimates of the complete shell range from
2.55 to 3.5 meters across. This are the largest known
examples, most others smaller.
Known locations: Across Europe and the USA.
Time period: Cenomanian to Campanian of the
Cretaceous.
Fossil representation: Many individuals.
Parapuzosia
was once named as a species of the Pachydiscus
genus in 1895 by
Hermann Landois, but was renamed as a distinct genus in 1913
establishing Parapuzosia seppenradensis as the
type species. Today
the species of the Parapuzosia genus are regarded
as the largest
ammonites that are currently known to us. The largest Parapuzosia
bradyi had a shell that measured one hundred and forty by one
hundred
and eighty centimetres, making it the largest species of Ammonite
known from North America.
Even
bigger though was Parapuzosia seppenradensis from
Europe. The largest
known shell of this has a maximum diameter of around one hundred and
eighty centimetres, but this is the measurement for the incomplete
shell. In life and when complete this shell is thought to have been
anything between two hundred and fifty-five centimetres and three
hundred and fifty centimetres across. Though the exact size of
Parapuzosia seppenradensis is a matter of debate,
it is still
regarded as the largest ammonite currently known to us.
Ammonites
like Parapuzosia are perceived to have been
pelagic (open water)
predators of other oceanic organisms. These may have included fish,
other cephalopods including squid and even other ammonites, as well
as possibly even smaller marine reptiles if they could catch them. As
far as locomotion goes, Parapuzosia would have
had a siphon pointing
out of the shell that could shoot out water like a jet, just like we
can see in other cephalopods such as squids, octopuses, cuttlefish
and nautilus. It’s probable that Parapuzosia may
have had a greater
range of vertical movement in the water column as opposed to distance
travel given that such behaviour has been observed in squid and
nautilus.
When
a Parapuzosia had a prey item such as a fish within
its tentacles,
the prey would have been manipulated and positioned to be near the
mouth. This would have been a strong, very tough beak that could
slice flesh as well as crush shells and bones. Parapuzosia
may have
been prey to other predators themselves however. When still growing
up they may have been preyed upon by sharks
with exceptionally tough
teeth like Cretoxyrhina,
as well as mosasaurs
such as Globidens
and
Prognathodon
which had specially adapted teeth for cracking and
breaking up the shells of armoured prey. Even larger Parapuzosia
may
not have been safe from the largest mosasaurs such as Tylosaurus
and
Mosasaurus
that through sheer size might have still had the jaw power
to break open a Parapuzosia shell.
Further reading
-Die Riesenammoniten von Seppenrade, Pachydiscus Zittel
Seppenradensis - Jahresbericht des Westf�lischen Provinzial-Vereins
f�r Wissenschaft und Kunst 23: 99–108. - H. Landois -
1895.
- Parapuzosia (Parapuzosia)
seppenradensis (Landois) und die
Ammonitenfauna der D�lmener Schichten, unteres Unter-Campan,
Westfalen. - Geologie und Pal�ontologie in Westfalen 33:
1–127 - W. J. Kennedy & U. Kaplan - 1995
- Ammonites and the Other Cephalopods of the Pierre Seaway. -
Geoscience Press, Inc. p. 44 - Neal L. Larson, Steven
D. Jorgensen, Robert A. Farrar & Peter L. Larson -
1997.
- Two-phase increase in the maximum size of life over 3.5 billion
years reflects biological innovation and environmental opportunity.
PNAS 106(1): 24–27 - Jonathan L. Payne, Alison G.
Boyer, James H. Brown, Seth Finnegan, Michał Kowalewski,
Richard A. Krause, Jr., S. Kathleen Lyons, Craig R.
McClain, Daniel W. McShea, Philip M. Novack-Gottshall,
Felisa A. Smith, Jennifer A. Stempien, and Steve C. Wang
- 2009.
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