A similar if more-exaggerated pattern of cresting appears in the so-called robust australopiths but not in Homo.
The degree of lophodonty of the molariform teeth increased, changing the pattern of the crests on the surface and increasing their grinding efficiency.
"When all the available information is put together, including the digital brain and ear casts, the evolutionary relationships, and the growth pattern of the crest and its high degree of variability in different coexisting species, it supports the idea that the elaborate nasal cavity was likely used to produce sounds for communication".
The seasonal pattern of nuchal crest variation observed here, could therefore just be a consequence of the unnaturally nutrient rich captive environment in which domestic native breeds are kept.
These studies have defined the pattern of cranial neural crest cell migration in mouse embryos and demonstrated that the frontal bone is of neural crest origin, whereas the parietal bone is of mesoderm origin.
We then imaged cells and staged them according to the staining pattern of Sycp3 and CREST (Page and Hawley 2004).
The migration and distribution patterns of neural crest (NC) cells reflect the distinct embryonic environments of the head and trunk: cephalic NC cells migrate predominantly along the dorsolateral pathway to populate the craniofacial and pharyngeal regions, whereas trunk crest cells migrate along the ventrolateral pathways to form the dorsal root ganglia.
In mice, expression of Alx3 is highly localized and the characteristic expression pattern suggests an important role in patterning of neural-crest derived mesenchyme and shaping of craniofacial structures [64].
Data from lineage tracing experiments, expression patterns of neural crest cell (NCC) marker genes and detection of apoptotic cells indicate that the malformation of bones in Prtg-deficient mice is due to increased apoptosis of rostral CNCCs (R-CNCCs).
Open image in new window Fig. 6 Scars of specimens E and F under SEM. a Smooth area of specimen E. b Crest of specimen E. c Trough of specimen E. d Uneven wear pattern of specimen F. e Crest of specimen F. f Trough of specimen F. The worn surfaces of specimens E and F, tested using rotation speeds of 32 and 94 rpm, respectively, exhibit uneven wear phenomena (Fig. 6).
