The Coal Measures Amphibia of North AmericaMoodie, Roy Lee
Science
The Coal Measures Amphibia of North America
Moodie, Roy Lee
Amphibians, Fossil -- North America; Paleontology -- Carboniferous; Paleontology -- North America
The skull is somewhat triangular in its general form. The premaxilla lies
on the anterior border of the cranium, and forms the median border of
the nostril. The suture which separates the maxilla and the premaxilla
is not evident, and it may not be correctly defined in the figure (fig.
23). The nasal is a very large element and is elongate. It unites with
the premaxilla, the lacrimal, the prefrontal, and the parietal. It
is acuminate behind and the point is inclosed by the pref rental and
the parietal. The frontal is quite narrow and elongate, and does not
border the orbit; its posterior boundary is not accurately represented.
The radiations on the surface indicate the extent of the element. The
parietals are remarkable in being smaller than the frontal and nasal. The
pineal foramen is inclosed in the median suture in the anterior third of
the parietals. The parietal has the usual relations of that element. The
postparietal lies posterior to the parietal, but a portion of its bounding
sutures are destroyed. The prefrontal forms the antero-interior border of
the orbit and borders the postfrontal posteriorly, in an unusual manner.
The lacrimal is a large element and is clearly separable from the other
cranial elements. It, with the prefrontal, forms the anterior border of
the orbit. The maxilla is very elongate and forms the larger part of the
lateral border of the skull. Sharp-pointed teeth are present on it and
they may have been pleurodont. The lateral border of the orbit probably
received a portion of the maxilla. The postfrontal and the postorbital
form the greater part of the posterior boundary of the orbit. The
postorbital seems to be divided by a median suture which would indicate an
intertemporal bone, but this is not certain. The appearance may be due to
a fracture. The supratemporal is a large element bordering the parietal
and lies in front of the tabulare. The squamosal is elongate to form the
posterior horn-like extension of the skull. The tabulare is transversely
elongate and has the usual relations. The jugal widens to a fan-shape
backwards, and helps to form the lateral border of the orbit. Its lateral
and anterior boundaries are not assured. The quadratojugal seems to lie as
indicated, although the anterior part of the suture is not distinct. It
is apparently an elongate element and with the maxilla forms the lateral
border of the skull. The base of the skull as restored (fig. 23) is
irregular and may have had a slightly different form.
The genus _Stegops_ is exceptional in the elongate character of the
cranial elements of the single species known. In this respect it recalls
the species _Diceratosaurus lævis_ described below. The large size of the
nasals, frontals, and lacrimals and the small size of the parietals are,
so far as I am aware, unparalleled among the other Coal Measures Amphibia
of North America.
Measurements of the Type.
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