A New Order of Fishlike Amphibia From the Pennsylvanian of KansasEaton, Theodore H. (Theodore Hildreth)
Science
A New Order of Fishlike Amphibia From the Pennsylvanian of Kansas
Eaton, Theodore H. (Theodore Hildreth)
Amphibians, Fossil; Paleontology -- Pennsylvanian
The new skeleton of _Hesperoherpeton_ lies in an oblong block of limy
shale measuring approximately 100 × 60 mm. After preparation of the
entire lower surface, the exposed bones and matrix were embedded in
Bioplastic, in a layer thin enough for visibility but giving firm
support. Then the specimen was inverted and the matrix removed from the
opposite side; this has not been covered with Bioplastic. The bones lie
in great disorder, except that some parts of the roof of the skull are
associated, and the middle section of the vertebral column is
approximately in place. The bones of the left forelimb are close
together but not in a natural position. The tail, pelvis, hind limbs
and right forelimb are missing. Nearly all the bones present are
broken, distorted by crushing, incomplete and scattered out of place,
probably by the action of currents. The complete skeleton, in life,
probably measured between 150 and 200 mm. in length.
The specimen was studied at the Museum of Natural History, University
of Kansas, with the help of a grant from the National Science
Foundation, number NSF-G8624. The specimen was discovered in the slab
by Miss Sharon K. Moriarty, and was further cleaned by the authors. Mr.
Merton C. Bowman assisted with the illustrations. We are indebted to
Dr. Robert W. Wilson for critical comments.
SKULL
_Dorsal Aspect_ (Figs. 1, 2)
In reconstruction, the skull measures approximately 8.0 mm.
dorsoventrally at the posterior end. The height diminishes anteriorly
to about 1.5 mm. at the premaxillary. The length is about 15.5 mm. in
the median line, or 24.0 mm. to the tip of the tabular, and the width
about 16.0 mm. posteriorly. The snout is blunt, continuing about 1-2
mm. anterior to the external nares. Each of the tabulars has a slender
posterior process 5.0 mm. long, which probably met the supracleithrum;
the intertabular space is about 8.5 mm. wide. The orbits are
approximately 5.5 mm. in diameter and extend from the maxillary to
within about 3.0 mm. of the midline dorsally. The pineal opening is 1.8
mm. anterior to the occipital margin of the skull.
Reduction of bones at the back of the skull seems to have eliminated
any dermal elements posterior to the squamosal, while enlargement of
the orbit has removed most of the postorbital series, leaving the
squamosal as the only cheekbone. There is apparently no jugal or
postfrontal.
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