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Acanthostega skull

Ben Creisler

New in PLoS ONE:

Laura B. Porro, Emily J. Rayfield & Jennifer A. Clack (2015)
Descriptive Anatomy and Three-Dimensional Reconstruction of the Skull
of the Early Tetrapod Acanthostega gunnari Jarvik, 1952.
PLoS ONE 10(3): e0118882
doi: 10.1371/journal.pone.0118882

The early tetrapod Acanthostega gunnari is an iconic fossil taxon
exhibiting skeletal morphology reflecting the transition of
vertebrates from water onto land. Computed tomography data of two
Acanthostega skulls was segmented using visualization software to
digitally separate bone from matrix and individual bones of the skull
from each other. A revised description of cranial and lower jaw
anatomy in this taxon based on CT data includes new details of sutural
morphology, the previously undescribed quadrate and articular bones,
and the mandibular symphysis. Sutural morphology is used to infer
loading regime in the skull during feeding, and suggests Acanthostega
used its anterior jaws to initially seize prey while smaller posterior
teeth were used to restrain struggling prey during ingestion. Novel
methods were used to repair and retrodeform the skull, resulting in a
three-dimensional digital reconstruction that features a longer
postorbital region and more strongly hooked anterior lower jaw than
previous attempts while supporting the presence of a midline gap
between the nasals and median rostrals.