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Re: Ancient Marine Reptile Growth Rates?
--- MariusRomanus@aol.com wrote:
> I have a question about the growth rates of marine
> reptiles. Now, I'm not talking about itty bitty
> modern sea turtles... What I've always been curious
> about are the estimates proposed for the bigger
> variety, like mosasaurs, plesiosaurs, etc. I have a
> few papers and books on marine reps (extinct and
> extant), but the subject of growth rates really
> aren't discussed (for the living versions, the data
> available is meager at best). Has any real work
> ever been done on the subject of ancient marine
> reptile growth rates? The largest sea turtles alive
> today (leatherbacks) only reach about 2m and
> 1400lbs... with 30 years of their lives spent
> reaching maturity (other species can take 50
> years!). For argument's sake, if you want to stick
> as close as you can to Mesozoic ocean-like temps, in
> the southern Bahamas, for example, green turtles
> only grow from 30 to 75 cm in 17 years, and there's
> indications that growth rates decrease with
> increasing carapace length.
Turtles are unique among vertebrates in general, in
that they tend to maintain very low metabolic rates
and take a long time to grow up (I blame all that
extra bone that has to be put down). So growth rate in
turtles should not be used as an indicator of growth
rate for all marine reptiles. Besides that, I still
question the estimates that are always given for sea
turtles. Especially for animals like leatherbacks, who
just disappear for their entire juvenile lives.
> All of this begs the question... How long did it
> take for an elasmosaurus to reach 14m with a weight
> of 2 tonnes? And for that matter, at what age did
> it begin to breed?
I don't know of any data for elasmosaurs, but Rodrigo
Pellegrini did some work on the skeletochronology of
mosasaurs. Unfortunately only an abstract is available
MOSASAUR GROWTH RATES, LONGEVITY AND AGE OF ATTAINMENT
OF SEXUAL MATURITY DERIVED FROM LIMB BONE
Rodrigo Pellegrini (2). Dept. of Geology, University
of Kansas, Lawrence, Kansas.
Skeletochronology has proven a useful and reliable
method for biological studies of modern monitor
lizards. For the first time, the paleohistology of the
limb bones of their extinct relatives, the mosasaurs
Tylosaurus, Clidastes, and Platecarpus, is analyzed.
The objective is to obtain paleobiological data such
as growth rate, longevity, age at sexual maturity and
thermoregulatory indications for each taxon. In
addition to lines of arrested growth (LAGs), a poorly
understood type of growth line (the supernumerary LAG)
is investigated and its possible significance
proposed. Although the osteo-histologies of mosasaurs
and modern monitors are distinct, the data obtained
suggests Tylosaurus, Clidastes, and Platecarpus grew
and lived as modern reptiles do. The differences in
the bone microstructure of modern monitors and
mosasaurs are a result of the distinct adaptive zone
that the latter occupied as large, fully marine
Perhaps HP Mike Everhart could suggest some more info
for the sauropterygians.
"I am impressed by the fact that we know less about many modern [reptile] types
than we do of many fossil groups." - Alfred S. Romer
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