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|Figs. 1-5. Rhabdosteus latiradix Cope.|
1) Lower view of rostrum. Charles County near the Patuxent River. Acad. Nat. Sci., Phila.
2) Upper view of another rostrum. Same locality and collection.
3a) Tooth from the anterior portion of the rostrum.
4a) Another tooth. Same locality and collection
5) Another tooth. Same locality and collection.
This family is peculiar in its group in that it possesses teeth of two kind as in the ARCHEOCETI; the anterior teeth are simple and conical while the posterior or molar teeth are more complex and are two-rooted (there are teeth in the premaxillary). The skull, however, presents the characters of the ODONTOCETI. There are no living members of this family.
Genus RHABDOSTEUS Cope.
Rhabdosteus latiradix Cope.
Rhabdosteus latiradix Cope, 1867, Proc. Acad. Nat. Sci. Phila., vol. xix, p. 132
(report of verbal communication), and pp. 144, 145.
Rhabdosteus latiradix Leidy, 1869, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. vii,
p. 435 (mention only).
Rhabdosteus latiradix Cope, 1890, Amer. Nat., vol. xxiv, p. 607, fig. 4, p. 615.
In the report of the verbal communication of Cope we find the following: "Rhabdosteus
latiradix Cope was a peculiar genus near the DELPHINIDAE, allied
to Priscodelphinus Leidy, and perhaps Platanista of the Ganges.
Characteristic of it was a muzzle formed of the usual elements but entirely
cylindrical, the alveolar series approximated underneath, and ceasing near the
middle. Beyond this the muzzle was prolonged like a cylindrical beak of a sword-fish,
or Coelorhynchus, and probably much farther than the mandible. Alveolae
longitudinal. Fragmentary specimens of this muzzle have been found by the discoverer
2.5 feet in length."
On page 145 of the same volume Cope gives the generic and specific description of the form. "This genus is either referable to a family not yet characterized, allied to the PLATANISTIDAE and DELPHINIDAE, or belongs to the first named of these recent families.
"Premaxillary and maxillary bones forming a cylinder, bearing teeth on its proximal portion, and prolonged in its distal portion into a slender straight beak. Teeth with the enlarged crown separated from the fang by a constriction."
The original description of the species is as follows: "A portion of the muzzle" of this species which is preserved, measures 12 inches 7.5 lines in length, 12.5 lines in transverse, and 11 lines in vertical diameter at the base.
"The superior edge of the maxillary bone forms the external outline, while the remainder of this element is entirely inferior. The palatine face is convex, and the alveolar series approximated. The alveolae themselves are longitudinal, two in 0.75 of an inch, and separated from each other by spongy septa. The vomer does not appear in the portion of the muzzle at my disposal.
Width of premaxillary ......................... 6 lines (12 mm.)
Width superior face of maxillary.......... 4.75 lines ( 9.50 mm.)
Width palatine face of maxillary .......... 4.5 lines ( 9 mm.)
"Three teeth are referred with much probability to this species. The fangs are from equal to twice the length of the crowns, and are much compressed, widening downwards, and more or less prolonged at one inferior angle, in the same plane. The crown, compressed transversely to the root, and expanded above the base, straight or slightly curved in the direction of its plane. Enamel smooth, edges obtuse. The compressed fang corresponds to the longitudinal alveolus while the transverse dilatation of the crown is similar to the form of those of Platanista.
Length of the longest specimen.........12 lines (24 mm.)
Length of the crown ....................... 5 lines (10 mm.)
Width of fang ................................. 3 lines ( 6 mm.)"
Occurrence. Calvert formation. Charles County near
the Patuxent river.
Collection. The type specimen is preserved in the Museum of the Academy of Natural Sciences of Philadelphia
(these web pages were prepared by R. D. Conkwright)