The skull of Morganucodon

Morganucodon is a triconodont (atherian) mammal from the Lower Jurassic. Two species are described: M. oehleri from China and M. watsoni from Wales. The skull in M. walsoni is 26 mm long; M. oehleri is slightly larger. The dentition is differentiated functionally into incisors, canines, premolars and molars. The pineal foramen is closed. The prefrontals, postfrontals and postorbitals are lost. Septomaxilla, quadratojugal, tabular and pterygoid flanges are retained. The bony external nares are unpaired. The nasal cavity had the mammalian complement of turbinals. The posterior palate has ridges and troughs similar to those in tritylodonts, triconodonts and multituberculates. The alisphenoid ascending process is narrow and is not in contact with the anterior lamina of the petrosal, lying lateral to it. There is a cavum epiptericum, as in late therapsids. The anterior lamina forms the lateral braincase wall, perforated by the foramina pseudovale and pseudorotundum. There is a squamosal-dentary articulation, but the reptilian jaw joint is retained. The ear resembles that in later therapsids, with the tympanum in the lower jaw. The small quadrate was moveable, buttressed medially be a large stapes. Sound conduction from the tympanum was via articular, quadrate and stapes. The systematic position of Morganucodon is discussed.     

Rigid-body analysis of a lizard skull: modelling the skull of Uromastyx hardwickii

Lizard skulls vary greatly in their detailed morphology. Theoretical models and practical studies have posited a definite relationship between skull morphology and bite performance, but this can be difficult to demonstrate in vivo. Computer modelling provides an alternative approach, as long as hard and soft tissue components can be integrated and the model can be validated. An anatomically accurate three-dimensional computer model of an Uromastyx hardwickii skull was developed for rigid-body dynamic analysis. The Uromastyx jaw was first opened under motion control, and then muscle forces were applied to produce biting simulations where bite forces and joint forces were calculated. Bite forces comparable to those reported in the literature were predicted, and detailed muscular force information was produced along with additional information on the stabilizing role of temporal ligaments in late jaw closing.     

Basicranial axis length v. skull length in analysis of carnivore skull shape

Skull length is the measurement most commonly used as a standard against which other aspects of cranial morphology are compared to derive an index of relative size or proportions. However, skull length is composed of two different functional components, facial skull and cerebral skull, which vary independently and have different scaling relationships with body size. An analysis of carnivore skull shape with measurements standardized against basicranium length produced very different results than an analysis using skull length as the standard. For example, expressions of relative size of cranial measurements were reduced by 13% in mustelids and increased by 20% in canids, reflecting removal of jaw length (short in mustelids and long in canids) from the comparative standard (basicranial axis length). Cranial measurements scale with higher allometric exponents against basicranial axis length than against skull length.     

Age changes of skull dimensions

At cranial level, external apposition during ageing has been postulated by some authors. In longitudinal studies, a gradual increase of cranial diameters has been shown by cephalometry (Kendrick et al. 1967) or by lateral radiography (Israel 1968, 1970). However, these results are contested at methodological level by other longitudinal studies (Tallgren 1974). It is the aim of this study to analyse, in a cross-sectional sample, the effects of senescence on several cephalic dimensions. A series of skulls of known age and sex has been selected for this purpose.     

The skull of Combe Capelle

Since the end of World War II two of the most important anthropological artefacts of the Museum für Vor- und Frühgeschichte in Berlin, the skulls and skeletons of Le Moustier and Combe Capelle, were believed to be missing or destroyed, respectively. The postcrania were severely damaged during a fire after the museum was bombed in February 1945, while the skulls were brought to the Soviet Union in 1945. In 1965, the skull of the Neanderthal man from Le Moustier and the chain of the grave of Combe Capelle were found amongst the art objects returned by the Soviet Union into the German Democratic Republic in 1958. However, the Combe Capelle skull was still missing. In the end of 2001 this skull could be found and identified in a store-house of the museum. Now, one the oldest known representatives of Homo sapiens sapiens is again available for scientific research and public exhibitions.     

Asymmetry in the skull.

Various linear and angular measurements were taken in 118 normal skulls of adult humans. The two halves of the skulls were found to be symmetrical. The phenomenon of asymmetry of various parts of the body, in relation to cerebral dominance and specific skills has been discussed in view of the findings of the study and in the light of the available literature.     

Considerations about the cloverleaf skull

The study of four cloverleaf skulls (two fetuses, one infant, and a young adult) concerns two Pfeiffer syndromes, a thanatophoric dysplasia and an isolated case. Clinical and radiologic examinations showed malformations at the level of the calvarium, the base, orbital cavities, and, sometimes, limb abnormalities. Correlations between these findings and the microradiographic analysis of nondemineralized sections elucidate this trilobular appearance of the skull. Premature temporoparietal suture closure terminates at a constricted surface of the lateral sides of the skull during the fetal life. Extension of the synostosis to coronal and frontal sutures and thickening of the occipital bone squama block lengthening of the skull. The consecutive reduction in skull volume is compensated by the maintenance of the permeability during the neonatal period of the sagittal and lambdoid sutures. Microradiographic examination shows that this anomaly may be of vascular origin and associated with abnormal osteoclastic resorption.     

Multi-dimensional complexes of skull traits

The simultaneous incidence of sutural bones was studied by a multidimensional analysis (Wanke method). On a medieval sample of 249 male and female skulls from Lower Austria the presence of two main complexes of sutural and fontanelle bones was observed. The interaction of possible genetic factors and developmental growth incongruences in causing these phenomena are discussed. The necessity of further studies considering such basic biological aspects with minor skeletal traits is stressed.     

Enameloma in a prehistoric Indian skull

Two enamel pearls or enamelomata are described and pictured on the molar tooth of a prehistoric Illinois Indian. One is at the cervical margin and the other is in the very rare location of the apical third of the root.