mechanism from the back of the braincase. The lower jaw
consists chiefly of the elongated angular and dentary
(tooth-bearing) processes, the latter being only loosely
connected by skin and ligaments at the chin.
palatines are aligned to support a row of teeth in the roof
of the mouth, the palatal teeth. The zig-zag and/or
dragging action (various feeding methods exist) of the
pterygoids and palatine bones, aided by the palatal teeth,
‘The zig-zag and/or dragging action of the pterygoids and
palatine bones move prey through the snake’s mouth in a
process called palatine walking.’
The top jaw, collectively called the palato-maxillary
apparatus, is also vastly different from ours. For a start,
snakes have two sets of teeth in their upper jaw. In snakes,
the palate consists of two elongate, parallel bones of the
upper jaw, the pterygoid bones, which are connected to
the articular bone by ligaments and sit below the base of
the braincase, or neurocranium. The pterygoids extend
into the roof of the mouth and terminate in extensions
known as the palatine bones. Both pterygoids and
move prey items through the snake’s mouth in a process
called palatine walking. This is largely accomplished by
muscles working the pterygoids directly against the brain-
case.
The rest of the top-jaw apparatus is more concerned with
prey capture than swallowing. The outer bones of the
upper jaw, the maxillae, are (like the dentary bones) only
loosely attached by ligaments at the snout, as well as
Skulls of Early Amniotes Showing the Pattern of
Temporal Openings that Distinguish Major Groups.
(a) anapsid, (b), synapsid, (c) diapsid and (d) parapsid or eurapsid skull conditions.
Key to abbreviations for bones:
a, angular; b, dentary; f, frontal; j, jugal; l, lacrimal; m, maxilla; n, nasal; p, parietal; pf, postfrontal;
pm, premaxilla; po, postorbital; prf, prefrontal; q, quadrate; qj, quadratojugal; sa, surangular;
sm, septomaxilla; sq, squamosal; st, supratemporal.
Modified by Janne Torkkola from Carroll, R., L. 1990, Vertebrate Paleontology and Evolution.
W. H. Freeman and Company, New York, 698pp.