Post by coherentsheaf on May 6, 2012 3:41:03 GMT -5
Since the internet is full of information about mosasaurs approaching 15, 18, or even 20m, I thought I woud take a skeptical stab at it.
The three species of Mosasaur that are most often claimed to reach that size are Mosasaurus hoffmanni, Tylosaurus proriger and Hainosaurus bernardi.
Mosasaurus hoffmanni
Claims of giant size of Mosasaurus hoffmanni go back to Lingham Soliar (1995), who wrote:
"The entire lower jaw is reliably estimated at 1600 mm.
Using a 1: 10 head to body ratio (see Russell 1967, p.
210 for M. maximus) the length of the whole animal is
estimated at 17.6 m, making it the largest marine
reptile known."
First he missaplied Russels 1:10 ratio, which Russel meant to apply between jaw length and total length:
This can be seen by comparing these two tables by Russel on page 209 and 210 respectively. The character F means jaw length in mm. Compare the specimen NJSM 11053:
This reduces the total length to 16m. However the 1:10 ratio seems not to be the most realistic guide, as Per Christiansen and Niels Bonde (2002) write:
"The relationship between overall length and skull length in
reconstructions of mosasaurids is 7.1–7.7 for Tylosaurus, 7.5 for Plotosaurus,
7.7 for Platecarpus, 8.1 for Clidastes and around 8.7
for Hainosaurus (Russell, 1967; Nicholls, 1988)."
Using this ratios I arrive at a total length in between 11.36m and 13.92m.
Hainosaurus bernardi
I completely agree with Lindgren (2005):
"The total length of the preserved vertebral column in
IRScNB R23 (the larger one of the two individuals) is 8.1 m.
Assuming that the vertebral column in IRScNB R23 is more-or-less
complete from the cranium until the end of the intermediate
caudal series, and adding yet another 2.5 m for the distal (missing)
portion of the tail (Williston, 1898, pl. 72), this gives a total column
length of approximately 10.6 m. Together with the 1.6 m
long skull, the vertebral column indicates an animal with a total
skeletal length of about 12.2 m, not 17 m, as estimated by Russell
(1967) or 15 m, as suggested by Lingham-Soliar (1995, 1998)."
Tylosaurus proriger:
Th largest Tylosaurus I know of is the Bunker Mosasaur, which is estimated at about twelve meters: www.oceansofkansas.com/KU-Bunker.html
Summary:None of the giant Mosasaurs live up to the legend
. I apologise for citing the paper by Lingham Soliar as evidence of trutly gigantic Mosasaurs.
Sources:
Russel (1967). "The Systematics and Morphology of American Mosasaurs"
Per Christiansen and Niels Bonde (2002). "A new species of giantMosasaur from the late Cretaceous of Israel"
Lindgren, Johan (2005) "The firs record of Hainosaurus (Reptilia:Mosasauridae) from Sweden"
Lingham-Soliar, T. (1995)."Anatomy and functional morphology of the largest marine reptile known, Mosasaurus hoffmanni (Mosasauridae, Reptilia) from the Upper Cretaceous, Upper Maastrichtian of The Netherlands"
The three species of Mosasaur that are most often claimed to reach that size are Mosasaurus hoffmanni, Tylosaurus proriger and Hainosaurus bernardi.
Mosasaurus hoffmanni
Claims of giant size of Mosasaurus hoffmanni go back to Lingham Soliar (1995), who wrote:
"The entire lower jaw is reliably estimated at 1600 mm.
Using a 1: 10 head to body ratio (see Russell 1967, p.
210 for M. maximus) the length of the whole animal is
estimated at 17.6 m, making it the largest marine
reptile known."
First he missaplied Russels 1:10 ratio, which Russel meant to apply between jaw length and total length:
This can be seen by comparing these two tables by Russel on page 209 and 210 respectively. The character F means jaw length in mm. Compare the specimen NJSM 11053:
This reduces the total length to 16m. However the 1:10 ratio seems not to be the most realistic guide, as Per Christiansen and Niels Bonde (2002) write:
"The relationship between overall length and skull length in
reconstructions of mosasaurids is 7.1–7.7 for Tylosaurus, 7.5 for Plotosaurus,
7.7 for Platecarpus, 8.1 for Clidastes and around 8.7
for Hainosaurus (Russell, 1967; Nicholls, 1988)."
Using this ratios I arrive at a total length in between 11.36m and 13.92m.
Hainosaurus bernardi
I completely agree with Lindgren (2005):
"The total length of the preserved vertebral column in
IRScNB R23 (the larger one of the two individuals) is 8.1 m.
Assuming that the vertebral column in IRScNB R23 is more-or-less
complete from the cranium until the end of the intermediate
caudal series, and adding yet another 2.5 m for the distal (missing)
portion of the tail (Williston, 1898, pl. 72), this gives a total column
length of approximately 10.6 m. Together with the 1.6 m
long skull, the vertebral column indicates an animal with a total
skeletal length of about 12.2 m, not 17 m, as estimated by Russell
(1967) or 15 m, as suggested by Lingham-Soliar (1995, 1998)."
Tylosaurus proriger:
Th largest Tylosaurus I know of is the Bunker Mosasaur, which is estimated at about twelve meters: www.oceansofkansas.com/KU-Bunker.html
Summary:None of the giant Mosasaurs live up to the legend
. I apologise for citing the paper by Lingham Soliar as evidence of trutly gigantic Mosasaurs.Sources:
Russel (1967). "The Systematics and Morphology of American Mosasaurs"
Per Christiansen and Niels Bonde (2002). "A new species of giantMosasaur from the late Cretaceous of Israel"
Lindgren, Johan (2005) "The firs record of Hainosaurus (Reptilia:Mosasauridae) from Sweden"
Lingham-Soliar, T. (1995)."Anatomy and functional morphology of the largest marine reptile known, Mosasaurus hoffmanni (Mosasauridae, Reptilia) from the Upper Cretaceous, Upper Maastrichtian of The Netherlands"
