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Sauropodomorph growth curves from long bone histological data



From: Ben Creisler
bcreisler@gmail.com


A new paper in PLoS ONE:



Eva Maria Griebeler, Nicole Klein &  P. Martin Sander (2013)
Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced
from Growth Curves Using Long Bone Histological Data: An Assessment of
Methodological Constraints and Solutions.
PLoS ONE 8(6): e67012.
doi:10.1371/journal.pone.0067012
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0067012


Information on aging, maturation, and growth is important for
understanding life histories of organisms. In extinct dinosaurs, such
information can be derived from the histological growth record
preserved in the mid-shaft cortex of long bones. Here, we construct
growth models to estimate ages at death, ages at sexual maturity, ages
at which individuals were fully-grown, and maximum growth rates from
the growth record preserved in long bones of six sauropod dinosaur
individuals (one indeterminate mamenchisaurid, two Apatosaurus sp.,
two indeterminate diplodocids, and one Camarasaurus sp.) and one basal
sauropodomorph dinosaur individual (Plateosaurus engelhardti). Using
these estimates, we establish allometries between body mass and each
of these traits and compare these to extant taxa. Growth models
considered for each dinosaur individual were the von Bertalanffy
model, the Gompertz model, and the logistic model (LGM), all of which
have inherently fixed inflection points, and the Chapman-Richards
model in which the point is not fixed. We use the arithmetic mean of
the age at the inflection point and of the age at which 90% of
asymptotic mass is reached to assess respectively the age at sexual
maturity or the age at onset of reproduction, because unambiguous
indicators of maturity in Sauropodomorpha are lacking. According to an
AIC-based model selection process, the LGM was the best model for our
sauropodomorph sample. Allometries established are consistent with
literature data on other Sauropodomorpha. All Sauropodomorpha reached
full size within a time span similar to scaled-up modern mammalian
megaherbivores and had similar maximum growth rates to scaled-up
modern megaherbivores and ratites, but growth rates of Sauropodomorpha
were lower than of an average mammal. Sauropodomorph ages at death
probably were lower than that of average scaled-up ratites and
megaherbivores. Sauropodomorpha were older at maturation than
scaled-up ratites and average mammals, but younger than scaled-up
megaherbivores.
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