INVESTIGADORES
TROTTEYN Maria Jimena
artículos
Título:
Osteoderm Histology of Proterochampsia and Doswelliidae (Reptilia: Archosauriformes) and Their Evolutionary and Paleobiological Implications
Autor/es:
CERDA, IGNACIO A.; DESOJO, J. B.; TROTTEYN, M. J.; SCHEYER, T. M.
Revista:
JOURNAL OF MORPHOLOGY
Editorial:
WILEY-LISS, DIV JOHN WILEY & SONS INC
Referencias:
Lugar: New York; Año: 2015
ISSN:
0362-2525
Resumen:
Postcranial osteoderms are commonly
developed in the major lineages of Archosauriformes,
including forms such as proterochampsids and doswelliids.
Here, we survey the histology of osteoderms of the
doswelliids Archeopelta arborensis and Tarjadia ruthae,
and the proterochampsids Chanaresuchus bonapartei and
Pseudochampsa ischigualastensis to understand better
the morphogenesis of these skeletal elements. Whereas,
the Doswelliid osteoderms possess a trilaminar organization,
in which two cortices (external and basal) can be differentiated
from an internal core of cancellous bone, these
elements are compact structures in proterochampsids.
The osteoderms of P. ischigualastensis are avascular and
they consist entirely of parallel-fibered bone. Conversely,
the osteoderms of C. bonapartei are well vascularized
structures composed of zones of woven-fibered bone and
annuli of parallel-fibered bone. The rather simple microstructure
observed in P. ischigualastensis osteoderms suggests
that these elements grew at a constant, low rate.
Compared with proterochampsids, doswelliid osteoderms
possess a more complex histology, which appears to be
linked to variations in the growth rate during the osteoderm
formation and also to the development of the external
ornamentation. A comparison of our findings with the
results of earlier studies on other archosauriforms (phytosaurs
and pseudosuchians) reveals that the general osteoderm
histology of doswelliids bears a closer resemblance
to that of phytosaurs and pseudosuchians than the proterochampsid
osteoderm microstructure. If all archosauriform
osteoderms are homologous structures, the closer
resemblance of doswellid osteoderm microstructures to
that of phytosaurs and pseudosuchians is in agreement
with the hypothesis that doswellids are more closely
related to archosaurs than proterochampsids.