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Cranial Anatomy (cranial + anatomy)

Distribution by Scientific Domains

Life Sciences	60%
Earth and Environmental Science	40%

Selected Abstracts

The internal cranial anatomy of the Plesiosauria (Reptilia, Sauropterygia): evidence for a functional secondary palate

LETHAIA, Issue 4 2006
Marie-Céline Buchy
In the late 19th Century, the choanae (or internal nares) of the Plesiosauria were identified as a pair of palatal openings located rostral to the external nares, implying a rostrally directed respiratory duct and air path inside the rostrum. Despite obvious functional shortcomings, this idea was firmly established in the scientific literature by the first decade of the 20th Century. The functional consequences of this morphology were only re-examined by the end of the 20th Century, leading to the conclusion that the choanae were not involved in respiration but instead in underwater olfaction, the animals supposedly breathing with the mouth agape. Re-evaluation of the palatal and internal cranial anatomy of the Plesiosauria reveals that the traditional identification of the choanae as a pair of fenestrae situated rostral to the external nares appears erroneous. These openings more likely represent the bony apertures of ducts that lead to internal salt glands situated inside the maxillary rostrum. The ,real' functional choanae (or caudal interpterygoid vacuities), are situated at the caudal end of the bony palate between the sub-temporal fossae, as was suggested in the mid-19th Century. The existence of a functional secondary palate in the Plesiosauria is therefore strongly supported, and the anatomical, physiological, and evolutionary implications of such a structure are discussed. [source]

Cranial osteology of the sauropterygian Plesiosaurus brachypterygius from the Lower Toarcian of Germany

PALAEONTOLOGY, Issue 1 2000
Michael W. Maisch
An osteological re-study of the holotype skull of Plesiosaurus brachypterygius leads to a correction of several inaccuracies and misidentifications of the original description by von Huene and reveals additional facts on the cranial anatomy of this plesiosaur. Comparison with the type species, Plesiosaurus dolichodeirus, from the Lower Lias of England shows considerable differences in many parts of the cranial skeleton, even though the two species are generally so similar that their inclusion in the same genus proposed by von Huene, and agreed with by all subsequent authors, can be supported. Plesiosaurus brachypterygius is provisionally considered as a valid species distinguishable from the contemporaneous Plesiosaurus guilelmiimperatoris by its much shorter limbs, a difference that cannot be explained by ontogenetic variation as proposed by Storrs. Plesiosaurus brachypterygius was probably an ichthyophagous form that occurred rarely in the Posidonienschiefer fauna. [source]

A comparative analysis of internal cranial anatomy in the hylobatidae

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010
Erin Rae Leslie
Abstract Craniometric studies on the hylobatids using external metrics (Creel and Preuschoft, 1976, 1984) sorted hylobatid populations into primary species groupings which are in accordance with the four currently recognized generic-level groupings. The goal of the current study was to assess the relative orientations of the orbits, palate, and basioccipital clivus among the hylobatid genera in an effort to further clarify whether the lesser apes differ significantly in these internal cranial features and how that variation patterns across the groups. Nine angular variables quantifying orbital, palatal, and basioccipital clivus orientations were measured on lateral view radiographs of adults representing three of the four hylobatid genera: Hylobates; Nomascus; and, Symphalangus. The interspecific adult hylobatid means for the angular variables were analyzed using t -test contrasts. The total sample was further subjected to discriminant function analysis (DFA) to test for the ability of craniofacial angular variables to distinguish the hylobatid genera from one another. The three hylobatid genera displayed significant morphological differentiation in orbital, palatal, and posterior skull base orientations. Normal, jackknifed, and cross-validation DFA procedures correctly identified the hylobatids 50,100% of the time. The observed morphological patterns generally mapped onto the findings of earlier external craniometric hylobatid studies and suggest concordance between specific internal and external cranial features. This article is the first comprehensive study of variation in internal cranial anatomy of the Hylobatidae and includes the first published craniofacial angular data for Nomascus. Am J Phys Anthropol 143:250,265, 2010. © 2010 Wiley-Liss, Inc. [source]

Human cranial anatomy and the differential preservation of population history and climate signatures

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 12 2006
Katerina Harvati
Abstract Cranial morphology is widely used to reconstruct evolutionary relationships, but its reliability in reflecting phylogeny and population history has been questioned. Some cranial regions, particularly the face and neurocranium, are believed to be influenced by the environment and prone to convergence. Others, such as the temporal bone, are thought to reflect more accurately phylogenetic relationships. Direct testing of these hypotheses was not possible until the advent of large genetic data sets. The few relevant studies in human populations have had intriguing but possibly conflicting results, probably partly due to methodological differences and to the small numbers of populations used. Here we use three-dimensional (3D) geometric morphometrics methods to test explicitly the ability of cranial shape, size, and relative position/orientation of cranial regions to track population history and climate. Morphological distances among 13 recent human populations were calculated from four 3D landmark data sets, respectively reflecting facial, neurocranial, and temporal bone shape; shape and relative position; overall cranial shape; and centroid sizes. These distances were compared to neutral genetic and climatic distances among the same, or closely matched, populations. Results indicate that neurocranial and temporal bone shape track neutral genetic distances, while facial shape reflects climate; centroid size shows a weak association with climatic variables; and relative position/orientation of cranial regions does not appear correlated with any of these factors. Because different cranial regions preserve population history and climate signatures differentially, caution is suggested when using cranial anatomy for phylogenetic reconstruction. Anat Rec Part A, 2006. © 2006 Wiley-Liss, Inc. [source]