There are other indicators of adulthood than sutures in plesiosaurs, discussed in the description of Pliosaurus funkei:
"In the vertebral column of PMO 214.135 and PMO 214.136,
none of the neural arches are fused to their centra. It is
noteworthy that the fusion of neural arches with vertebral
centra has not been observed in any of the Pliosaurus
specimens examined in this study, nor has this been previously
reported for any other of the large pliosaurids (e.g., Philips,
1871; Tarlo, 1959 a and b; 1960; Halstead, 1971; Buchy, 2007),
and it is therefore difficult to determine whether this is truly
a reliable indicator of a juvenile or whether it is possibly a
paedomorphic feature in pliosaurids. The humerus of PMO
214.135 has a distinct tuberosity that is partially separated
from the capitulum, suggesting it is a mature individual
(Brown, 1981). The coracoid bears a well developed anterior
process, normally seen in adult specimens, when present
(pers. obs., EMK). Wiffen et al. (1995) discussed potential
histological indicators of ontogeny in a Late Cretaceous
elasmosaurid and a pliosauroid. They noted that adult
specimens had an osteosclerotic pattern of growth compared
to the pachyosteosclerotic bones of juveniles (but see
discussion in Liebe & Hurum, 2012).
The cervical vertebral
centra of PMO 214.135 and PMO 214.136 display a clear
osteosclerotic state with a very spongy internal structure. Thus,
morphological and histological characters indicate that both
Svalbard specimens were adult individuals."It would be helpful to verify if this condition is present or not in the Monster of Aramberri.
It seems clear that unfused vertebral sutures cannot be considered an indication of juvenile stage in pliosaurs but the question would be to found if the Monster of Aramberri represents an adult in every other aspect of its anatomy.
Btw, I've actually found one scientific mention of a TL about 18 m from the authors for the MoA but what they meant by this is unclear because it's in contradiction with their first estimate of 15 m. Maybe they suggested 18 m as a full grown size back then ?
Was it really eating granite? We're searching hard: history of the Monster
of Aramberri (and stories about it).
M.-C. Buchy & E."D." Frey, Geowissenschaftliche Abteilung, Staatliches Museum für
Naturkunde, Erbprinzenstrasse 13, D-76133 Karlsruhe, Germany, and Universität Karlsruhe,
Geologisches Institut, Postfach 6980, D-76128 Karlsruhe, Germany.
mcbuchy@compuserve.com
On the 28th of December 2002, the German magazine Der Spiegel published a 2-page article about a
large pliosaur from Mexico nicknamed "the Monster of Aramberri"1, 2, launching a long-lasting
multimedia campaign of "godzillaisation"3
. When the remains of the beast reached the State Museum
of Natural History of Karlsruhe where it will be prepared and studied, it had became a 25 meter-long
Liopleurodon ferox biting through granite.
Seven aligned vertebrae and a piece of jaw, found in 1985 by a student of the Autonomous University
of Nuevo León, Linares, Mexico, were first identified as belonging to a carnivorous dinosaur4
. We
rediscovered the fossil in autumn 2000, and, on the basis of its pectoral vertebrae 22 cm in diameter,
estimated the length of the pliosaur at about 15 meters1, 2.
A field campaign was conducted the year after as a collaboration between the State Museum of
Natural History of Karlsruhe, the University of Karlsruhe and the Autonomous University of Nuevo
León, financed by the Deutsche Forschungsgemeinschaft. It yielded isolated cranial fragments, and the
original pliosaur-bearing layer was identified. During the campaign 2002 we collected the head of a
femur about 30 cm in diameter, part of the pelvic girdle, and more cranial fragments. We shall
continue digging for some years before recovering the rest of the animal, which actually could have
reached 18 meters in length, and certainly does not belong to the genus Liopleurodon. No hint allows
to confirm, though, that it was chewing granite. We present here the history of the discovery and
rediscovery, and a preliminary report of the field campaigns.
1. Frey E., Buchy M.-C. & Stinnesbeck W. (2001) – The monster of Aramberri and friends: new finds
of marine reptiles in the Mesozoic of northeastern Mexico. 6th EWVP, Florence (Italy), 19-22
september 2001, Abstract Book.
2. Buchy M.-C., Frey E., Stinnesbeck W. & López-Oliva J.G. (in press) – First occurrence of a
gigantic pliosaurid plesiosaur in the Late Jurassic (Kimmeridgian) of Mexico. Bull. Soc. Geol. France.
3. Richard Forrest's ultimate plesiosaur site:
www.plesiosaur.com4. Hähnel W. (1988) – Hallazgo de restos de dinosaurio en Aramberri, N.L., Mexico. Actas Faculta
Ciencias Tierra UANL Linares, 3: 245-250.
