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Hungarian pterosaur diversity



From: Ben Creisler
bcreisler@gmail.com

A new online paper:

Edina Prondvai, Emese R. Bodor, and Attila Osi (2014)
Does morphology reflect osteohistology-based ontogeny? A case study of
Late Cretaceous pterosaur jaw symphyses from Hungary reveals hidden
taxonomic diversity.
Paleobiology 40(2):288-321
doi: http://dx.doi.org/10.1666/13030
http://www.bioone.org/doi/abs/10.1666/13030

With a single complete mandible and 56 mandibular symphyseal fragments
of various sizes, the Late Cretaceous Hungarian azhdarchid material
has been considered one of the most extensive monospecific pterosaur
assemblages in the world. Representing a broad size range, these
elements have been thought to demonstrate a developmental series of
Bakonydraco galaczi. As such, they were ideal to test whether absolute
size and/or morphology reliably indicate relative ontogenetic stages
in this pterosaur. Forty-five specimens were selected for multivariate
morphometrics and classified into four size classes. After acquiring
the morphometric data set, we thin-sectioned eight symphyses
representing all size groups and classified them into relative
ontogenetic stages based on qualitative microstructural inspection
prior to quantitative histological analyses. Microstructural
characters suggestive of developmental state were then quantified for
intra- and interindividual uni- and multivariate analyses to test the
correspondence among the results of qualitative and quantitative
analyses. In contrast to our expectations, histological features
identified the smallest specimen as an adult and not an early
juvenile. The substantial size difference between this specimen and
other adults, along with its distinct microanatomical and histological
features, implies the presence of at least two pterosaur taxa in this
symphysis assemblage. This hypothesis is further supported by
multivariate morphometrics, which separate the smallest symphyses from
all other specimens that form one continuous group. Although the
latter group also shows considerable size variability in corresponding
ontogenetic stages, this suggests developmental plasticity rather than
the presence of even more taxa, and indicates that symphysis size and
morphology are poor indicators of skeletal maturity in these animals.
Hence, bone histology is an important independent test of the
assessment of ontogenetic stage using size and morphology.