Shark Fossils

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Fig. 1. Carcharias (Prionodon) egertoni (Agassiz).
	la) Inner face of a well-preserved specimen of average size. Charles County near the Patuxent River. Acad. Nat. Sci., Phil
Fig. 2. Carcharias laevissimus (Cope).
	2) Inner face of a tooth. Fairhaven.
Figs. 3-5. Carcharias collata n. sp. (Ex. Cope MS).
	3a) Outer face of a posterior tooth with expanded root. (Type specimen.) Charles County near the Patuxent River. Acad. Nat. Sci., Phila. 3b) Inner face of the same specimen. 4a) Outer face of a large-sized tooth with erect crown and sharp lateral carinae. (Type specimen.) Acad. Nat. Sci., Phila. 4b) Inner face of the same specimen. 5) Inner face of an average-sized tooth with prominent root. (Type specimen.) Charles County near the Patuxent River. Acad. Nat. Sci., Phila.
Figs. 6, 7. Carcharias magna (Cope).
	6a) Outer face of a specimen with narrow root. Charles County near the Patuxent River. Acad. Nat. Sci., Phila. 6b) Inner face of the same specimen. 7a) Outer face of a large-sized lateral tooth with oblique crown and faint crimping of its basal edges. Charles County near the Patuxent River. Acad. Nat. Sci., Phila. 7b) Inner face of the same specimen.
Fig. 8. Carcharias incidens n. sp.
	8) Inner face of the type specimen. Chesapeake Beach.
Figs. 9a, 9b. Galeocerdo contortus Gibbes.
	9a) Outer face of a specimen slightly above the average size. Fairhaven. 9b) Inner face of the same specimen.
Fig. 10. Galeocerdo latidens Agassiz.
	10) Inner face of an average-sized tooth. Charles County near the Patuxent River. Acad. Nat. Sci., Phila.
Fig. 11. Galeocerdo aduncus Agassiz.
	11) Inner face of an averaged-sized tooth. Plum Point.
Fig. 12. Galeocerdo triqueter n. sp.
	12) Inner face of the type and only known specimen. Charles County near the Patuxent River. Acad. Nat. Sci., Phila.
Figs. 13, 14. Hemipristis serra Agassiz.
	13a) Outer face of a medium-sized anterior tooth. Popes Creek. 13b) Inner face of the same specimen. 14a) Outer face of a moderate-sized lateral tooth. Popes Creek. 14b) Profile of the same specimen. 14c) Inner face of the same specimen.
Fig. 15. Sphyrna prisca Agassiz.
	15) Inner face of a large-sized, perfectly preserved specimen. Plum Point.
Fig. 16. Sphyræna speciosa Leidy.
	16) Crown of fragmentary laniary tooth. Charles County near the Patuxent River. Acad. Nat. Sci., Phila.
Figs. 17-19. OTOLITES of Teleost Fishes.
	Inner, outer and side-views of otolites. St. Mary's River.

Family CARCHARIIDAE Müller and Henle.

     It is a noteworthy fact that the gradual decline of the LAMNIDAE during Tertiary time was accompanied by a remarkable increase in importance of the genera included under the CARCHARIIDAE, and evidence is not lacking to show the latter have been able to displace the LAMNIDAE by means of their more efficient organization. Although their dentition does not appear formidable in comparison with the gigantic teeth of Carcharodon, it is in reality more durable, making up in structure what it lacks in size. In the teeth of this family the nutrient canals are concentrated into a central pulp-cavity, and the greater part of the crown consists of vasodentine. Not only is there much variation among the teeth of the upper and lower jaws, but it often happens that teeth of the upper jaw in one species have the same form as those of the lower jaw in a different species, thus rendering the determination of isolated fossil teeth very uncertain. ¹

Genus Carcharias Cuvier.
Carcharias (Prionodon) egertoni (Agassiz).

Corax egertoni Agassiz, 1843, Poiss. Foss., vol. iii, p. 228, pl. xxxvi, figs. 6, 7.
Glyphis subulata Gibbes, 1847, Proc. Acad. Nat. Sci. Phila., vol. iii, p. 268.
Galeocerdo egertoni Gibbes, 1849, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 192,
          pl. xxv, figs. 66-69.
Glyphis subulata Gibbes, 1849, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 194,
          pl. xxv, figs. 86, 87.
Galeocerdo egertoni Emmons, 1858, Rept. N. Car. Geol. Survey, p. 238, fig. 90.
Carcharhinus (Prionace) egertoni Hay, 1902, Bull. 179, U.S. Geol. Survey, p. 312.

     Description.— "Upper teeth broad, triangular, prominently serrated, both margins slightly concave. Lower teeth probably narrower than the upper, robust and prominently serrated."
     This species occurs in about equal abundance with the teeth of Galeocerdo contortus and Sphyrna prisca, which accompany it at Plum Point, Fairhaven, Charles County, and other Maryland localities. Water-worn examples often show the characteristic hollow crowns.
     Occurrence.— Calvert formation. Fairhaven, Charles County near the
                Patuxent river, Chesapeake Beach.
     Collections.— Maryland Geological Survey, Philadelphia Academy of Natural Sciences.

Carcharias laevissimus (Cope).

Galeocerdo laevissimus Cope, 1867, Proc. Acad. Nat. Sci. Phila., vol. xix, p. 141.
Galeocerdo laevissimus Hay, 1902, Bull. 179, U.S. Geol. Survey, p. 311.

     Description.— A species only distinguished from C. egertoni by the absence of serrations on the coronal edges. Some teeth have the form of Galeocerdo latidens and G. aduncus, except that there are no denticulations.
     At first sight these teeth might appear to be only worn examples of C. egertoni, or even of Galeocerdo (although the posterior notch is never conspicuous), but a study of numerous specimens shows that in all probability the species is well founded. It is found at the same localities as the preceding form. The original of Plate XXXII, Fig. 2, is one of Cope's type-specimens, and the first of this species to be figured.
     Occurrence.— Calvert formation. Charles County near the Patuxent river, Fairhaven.
     Collections.— Maryland Geological Survey, Philadelphia Academy of Natural Sciences.

Carcharias collata n. sp. (ex Cope MS.).

     Description.— A species of moderate size, the teeth comparatively stout, with a narrow, usually erect crown, strongly convex on its inner and slightly so on its outer face; apex sometimes slightly curved inwards or backwards; coronal edges with extremely minute serrations disappearing toward the base. The enamel at base of crown extends much lower down in the middle of the outer than on the inner face. The root is considerably elongated, large and symmetrical.
     The Thomas Collection belonging to the Philadelphia Academy of Natural Sciences contains about forty teeth of Carcharias which were evidently regarded by Cope as indicating a new species, since they bear his MS. label " Sphyrna collata," a title which is now made valid by the above description. Fifteen other teeth are preserved in the same collection under a different specific title, also unpublished, but a careful examination fails to reveal any important character by which they may be distinguished from the first lot. All of these specimens are from Charles County.
     Under the name of Prionodon antiquus, two teeth of Carcharias, one with serrated and the other with unserrated edges, were described by Louis Agassiz ² from the Tertiary of California, and ascribed by him to the upper and lower jaws of one and the same species. As far as can be determined from the published figures, this association does not appear to be justified, and the evidence of Carcharias egertoni and C. collata would go to show that two distinct species are represented. If such a division were to be made, the form with serrated edges shown in Agassiz's Plate I, Fig. 15, should be selected as the type of C. (Prionodon) antiquus, while the others with sharp narrow crowns like that shown in Fig. 16 of the same plate should be transferred to C. collata, which they closely resemble, or else should receive a new specific name.
     Occurrence.— Choptank formation. Jones Wharf, Dover Bridge. Calvert formation.
                Charles County near the Patuxent river, Plum Point, Fairhaven, Chesapeake Beach.
     Collections.— Maryland Geological Survey, Philadelphia Academy of Natural Sciences.

Carcharias magna (Cope).

Sphyrna magna Cope, 1867, Proc. Acad. Nat. Sci. Phil., vol. xix, p. 142.
Sphyrna magna Hay, 1902, Bull. 179, U.S. Geol. Surrey, p. 314.

     Description.— Teeth of comparatively large size, attaining a total height of nearly 2 cm., and distinguished from C. collata by their wider, Oxyrhina-like crown and shorter root. Coronal edges sharp, non-serrated, or only slightly crimped at the base; enamel at base of crown much extended laterally over the root, which is short and considerably thickened on the inner face.
     This species is established on three somewhat dissimilar teeth from the Miocene of Charles County, which are remarkable for their large size as compared with other species of Carcharias and Sphyrna. Owing to the width of the crown and the extension of its basal portion over the root, a certain resemblance to the teeth of Oxyrhina is to be noted, but the nearest affinities are evidently with the foregoing species. As in that form, the root extends high up on the inner face, but is low on the outer.
     Occurrence.— Calvert formation. Charles County near the Patuxent river.
     Collection.— Philadelphia Academy of Natural Sciences.

Carcharias incidens n. sp.

     Description.— Teeth robust, triangular, prominently serrated along the entire coronal margin on both sides. Posterior margin only slightly concave, the anterior nearly straight. Root deep, not produced beyond the base of the crown on either side.
     The unique example on which this species is founded resembles in general form certain species of Corax from the Cretaceous, and is readily distinguished from other teeth pertaining to Carcharias, the roots of which are expanded and the coronal margins less prominently and completely serrated. The form under consideration also bears some resemblance to that described by Noetling as Galeocerdo dubius, from the Prussian Eocene.³ Both faces of the crown are convex, the inner more so than the outer. The total height of the tooth is 14 mm., the width 15 mm., and thickness of the crown at the middle of the base 4 mm.
     Occurrence.— Calvert formation. Chesapeake Beach.
     Collection.— Maryland Geological Survey.

Genus Galeocerdo Müller and Henle.
Galeocerdo contortus Gibbes.

Galeocerdo contortus Gibbes, 1849, Jour. Acad. Nat Sci. Phil., 2nd ser., vol. i, p.
           193, pl. xxv, figs. 71-74.
Galeocerdo contortus Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4.
Galeocerdo contortus Clark, 1896, Bull. 141, U.S. Geol. Survey, p. 62.
Galeocerdo contortus Woodward, 1889, Rept. N. Cat. Fos. Fishes, Brit. Mus., pt.1, p.443.

     Description.— "A species of moderate size. Teeth very robust, with elevated crown; the apex above the posterior notch elongated, produced to a sharp point, more or less twisted; anterior margin arched, somewhat sinuous, and finely serrated; margin below the posterior notch short, with comparatively small serrations."
     The teeth of this species are quite abundant in the Eocene of South Carolina, Alabama and Virginia, and occur somewhat plentifully in the Miocene of Maryland and adjoining states. The illustration given in Plate XXXII, Fig. 9, is of an average-sized individual.
     Occurrence.— Choptank formation. Greensboro. calvert formation. Charles County
                  near the Patuxent river, Fairhaven, 3 miles south of Chesapeake Beach, Plum Point.
      Collections.—Maryland Geological Survey, Philadelphia Academy of Natural Sciences,
                  Museum of Comparative Zoology.

Galeocerdo latidens Agassiz.

Galeocerdo latidens Agassiz, 1843, Poiss. Foss., vol. iii, p. 231, pl. xxvi, figs. 22, 23
           (? figs. 20, 21).
Galeocerdo latidens Eastman, 1901, Md. Geol. Survey, Eocene, p. 109, pl. xiv, fig. 8.

     This species is of rare occurrence in the Maryland Tertiary, only a single example being known from the Nanjemoy formation (Eocene) of Woodstock, and scarcely a dozen from the Miocene of Fairhaven and Charles County. The teeth exhibit considerable variation in form, some of them approaching closely to the type of G. aduncus except that they are more strongly serrated on the posterior margin (cf. Plate XXXII, Figs. 10, 11).
     Occurrence.— Choptank formation. Governor Run. Calvert formation. Fairhaven,
                 Charles County near the Patuxent river.
     Collections.— Maryland Geological Survey, Philadelphia Academy of Natural
                 Sciences, Museum of Comparative Zoology.

Galeocerdo aduncus Agassiz.

Galeocerdo aduncus Agassiz, 1843, Poiss. Foss. vol.iii, p. 231, pl. xxvi, flgs. 24-28.
Galeocerdo aduncus Gibbes, 1849, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 191,
            pl. xxv, flgs. 54-58.
Galeocerdo productus Agassiz, 1856, Rept. Pac. R. R. Expl. and Surv., vol. v, p. 314,
            pl. i, figs. 1-6.
Galeocerdo productus Agassiz, 1856, Amer. Jour. Sci., ser. ii, vol. xxi, p. 273.
Galeocerdo latidens Emmons (errore) 1858, Rept. N. Car. Geol. Survey, p. 839, fig.
            68 (non fig. 69; cuts 68 and 69 interchanged).
Galeocerdo aduncus Woodward, 1889, Rept. N. Cat. Fos. Fishes, Brit. Mus., pt.1, p.445.

      Description.— "A species with the dentition very similar to that of the existing G. arcticus but of smaller size. Anterior coronal margin much arched and finely serrated; the apex above the posterior notch short, broad, and sharply directed backwards; margin below the posterior notch relatively short in the principal teeth, with large serrations."—A. S. Woodward.
      The teeth of this species occur with rather more frequency than those of G. latidens, but are by no means abundant. The specimen shown in Plate XXXII, Fig. 11, is an average-sized specimen of one of the principal teeth.
     Occurrence.— Calvert formation. Charles County near the Patuxent river,
                 Plum Point, Fairhaven.
     Collections.— Maryland Geological Survey, Philadelphia Academy of
                 Natural Sciences, Museum of Comparative Zoology.

Galeocerdo triqueter n. sp. (ex Cope MS.).

     Description.— Teeth very robust, with elevated crowns, smaller and less twisted than those of G. contortus, and more faintly serrated along the coronal edges. Anterior margin only slightly arched, posterior notch inconspicuous. Root similar to that of G. contortus, and general aspect suggestive of Oxyrhina macrorhiza from the Lower Cretaceous. Height of crown in median line on outer face of the type-specimen 9 mm., on the inner face 6 mm., thickness of crown at its base 3.5 mm., thickness of root 5 mm.
     The somewhat worn specimen upon which this species is founded appears to be unique, nothing like it having been found since the Thomas Collection, of which it forms a part, was first brought together. The trivial title adopted for it is taken from a manuscript label of Cope's attached to the specimen, which bears witness that he regarded it as a distinct species, although its description was for some reason omitted. Possibly this is the same specimen which is listed as "Galeocerdo ? sp. aff. contorto" in connection with his description of G. laevissimus.⁴ What species is meant by his citation in the same place of the nomen nudum, "Galeocerdo appendiculatus Ag." cannot now be even conjectured, as there are no specimens in the collection bearing that designation.
     Occurrence.— Calvert formation. Charles County near the Patuxent river.
     Collection.— Philadelphia Academy of Natural Sciences.

Genus Hemipristis Agassiz.
Hemipristis serra Agassiz.

Hemipristis serra Agassiz, 1843, Poiss. Foss., vol. iii, p. 237, pl. xxvii, figs. 18-30.
Hemipristis serra Gibbes, 1849, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 193,
          pl. xxv, figs. 75-85.
Lamna (Odontaspis) hopei Gibbes (non Agassiz), 1849, Jour. Acad. Nat. Sci. Phila.
          2nd ser., vol. i, p. 198, pl. xxvi, figs. 120-123.
Hemipristis heteropleurus Agassiz, 1856, Rept. Pac. R. R. Explor. and Survey, vol. v,
          p. 315, pl. i, fig. 14.
Hemipristis heteropleurus Agassiz, 1856, Amer. Jour. Sci., ser. ii, vol. xxi, p. 274.
Hemipristis serra Emmons, 1858, Rept. N. Car. Geol. Survey, p. 235, fig. 63.
Hemipristis crenulatus Emmons, 1858, Rept. N. Car. Geol. Survey, p. 235.
Hemipristis serra Woodward, 1889, Rept. N. Cat. Fos. Fishes, Brit. Mus., pt.1, p.450.

     Description.— "Marginal serrations in the broad upper teeth large, extending almost to the apex, which is gently curved backwards. Cutting edges of the anterior lower teeth very sharp distally. Inner face of the root bulging inwards, with a deep cleft."
     This easily recognized species occurs in considerable abundance in the Eocene of South Carolina and Miocene of more northerly regions, extending as far as the cliffs of Gay Head on Martha's Vineyard. The lateral teeth are broad-based, strongly elevated along the middle of the inner face, and prominently serrated along the lateral edges. The serrations are oblique, rather more prominent on the posterior cutting-edge than on the anterior, and increase in size from the base of the crown to a point near the apex, where they cease altogether.
     The anterior teeth (Plate XXXII, Fig. 13) are stout and narrow, convex on both faces, between 3 and 4 cm. in total height, and with fewer and more irregular serrations than the lateral teeth. Many of these piercing teeth have the serrations reduced to slender cusps, more or less separated, and confined principally to the basal portion of the crown. The latter are obviously of different nature and origin from lateral denticles, properly so called, being merely retrogressive modifications of the cutting edge, and hence only of secondary importance, whereas lateral denticles represent the serial multiplication of entire crowns. Worn specimens of the anterior teeth are readily distinguished from Lamna and other forms by the pronounced swelling on the inner face of the root.
     A large series of teeth has been collected from Charles County and other well-known Miocene localities in this and adjoining states. As is true also of Oxyrhina desorii and Carcharodon megalodon, the Eocene examples from South Carolina seem to have attained a somewhat larger size than their Miocene successors.
     Occurrence.— Calvert formation. Plum Point, Fairhaven, Popes Creek,
                Charles County near the Patuxent river.
     Collections.—Maryland Geological Survey, Johns Hopkins University,
                 Philadelphia Academy of Natural Sciences.

Genus Sphyrna Rafinesque.
Sphyrna prisca Agassiz.

Sphyrna prisca Agassiz, 1843, Poiss. Foss., vol. iii, p. 234, pl. xxvi a, figs. 35-50.
Sphyrna denticulata Emmons, 1858, Rept. N. Car. Geol. Survey, p. 241, fig. 84a.
Sphyrna prisca Eastman, 1901, Md. Geol. Survey, Eocene, p. 110, pl. xiv, fig. 7.

     The small, pointed and finely serrated teeth of this " Hammerhead shark " are met with quite frequently in the principal Miocene localities of this and adjoining states. It is very abundant in the Eocene of South Carolina, but the specimens figured under this name by Gibbes ⁵ have the appearance of belonging to Carcharias rather than to Sphyrna. Only two or three teeth of this species have been obtained from the Eocene of Maryland.
     Occurrence.— Calvert formation. Plum Point, Charles County near
                 the Patuxent river, Chesapeake Beach.
     Collections.— Maryland Geological Survey, Philadelphia Academy of
                 Natural Sciences, Museum of Comparative Zoology.

UNDETERMINED SELACHIAN REMAINS.

     Under this head a brief reference may be made to detached vertebrae and fragments of Selachian armor, such as dermal tubercles and spines, which are occasionally met with in Miocene strata. As a rule, the partially calcified vertebrae are not well preserved, and worn examples are quite impossible to determine. An exceptionally perfect centrum from the Calvert formation at Plum Point is represented in Plate XXXI, Figs. 4a, 4b, and this appears referable with tolerable certainty to the genus Carcharodon. Although the presence of Raja, Trygon, Myliobatis, etc., is indicated by other remains, no vertebrae of the Batoid type have been found in this state, and even Teleostome vertebrae are rare.
     The spine shown in Plate XXIX, Fig. 4, has already been noticed in the discussion of Myliobatis remains (v. supra). Less perfect spines of equally large size from the Miocene of Richmond, Virginia, are described by Leidy,⁶ and referred by him rather doubtfully to the genera Trygon and Myliobatis. This author also describes in the same place, and from the same locality as the last, a dermal scute of Acipenser ornatus, and jaw-fragments of Protautoga conidens, but neither of these forms are known to occur in Maryland.

Subclass TELEOSTOMI.
Order ACTINOPTERYGII.

     The only species of bony fishes recorded from the Miocene of this state is "Sphyraena speciosa Leidy,"⁷ represented by a single laniary tooth from Charles County, of which a figure is given in Plate XXXII, Fig. 16. This and an allied form described by Cope under the name of Sphyrcaenodus silovianus occur in the Miocene of New Jersey in company with three other Actinopterygians, as follows: Phyllodus curvidens Marsh, Crommyodus irregularis Cope, and Phasganodus gentryi Cope. The Eocene and Miocene of Virginia combined yield scarcely a half-dozen species of bony fishes, and this group is represented with equal meagerness in North and South Carolina. In all these states, however, and especially in the Eocene of Alabama and Mississippi, Teleostome otolites (Plate XXXII, Figs. 17, 18, 19) occur in considerable abundance and variety; and it happens that these insignificant appearing objects are the only record that remains of a once flourishing fish-fauna, which can be but inadequately reconstructed in imagination. Many of the Miocene otolites occurring in this state are indistinguishable from those figured under a variety of titles from the Eocene of Alabama and Mississippi by Koken.⁸
     The problematical genus Ischyrhiza, to which attention was directed in the Eocene volume, may be dismissed with the statement that Cope's ⁹ reiterated assertion that " this or an allied genus is quite abundant in the Miocene of Maryland " remains up to the present time entirely uncorroborated. It is evident that this remark of Cope's applies only to the fused caudal fans, since he states immediately afterwards that " the teeth of the species have not been obtained." As for the tooth described by Leidy from North Carolina under the name of I. antiqua, Cope suggests it may have been a derived fossil of Cretaceous age, instead of Miocene. There is accordingly some reason for doubt whether either the teeth or the fans really continue into the Miocene, although they are unquestionably present in the Eocene. As already set forth in the preceding volume on the Eocene, the theoretical association of these teeth and fans under a single genus appears decidedly improper, and unwarranted by any facts. The name Ischyrhiza should be restricted to include only the teeth such as were first described by Leidy; and as for the fans, since they in all likelihood belonged to some of the Sword-fish tribe, they may be provisionally assigned to the genus Xiphias.

¹ Bei den Carchariden erschwert jene Verschiedenheit der Zähne in Ober- und Unterkiefer die specifische Bestimmung einzelner Zähne ungemein, weil häuflg die Zahnformen des einen Kiefers einer Art im entgegengesetzten Kiefer einer nahe verwandten Art wiederkehren. Man muss sich infolge dessen zunächst inyner klar zu machen suchen, ob man es mit einen oberen oder einem unteren Zähne zu thun hat. Eine Entscheidung hierüber ist zwar nicht immer möglich, aber im Allgemeinen machen sich doch die Zähne des Unterkiefers durch einen gedrungenen, kräftigen Ansatz der Krone kenntlich.
     Auf die Kerbung der Seitenkanten hat man unstreitig einen viel zu hohen systematischen Werth gelegt, indem man allein daraufhin Carcharias in Untergattungen trennte. Es liegt auf der Hand, dass eine solcbe Differenzlerung überall und sehr leicht eintreten kann, und dass es vielfach nicht möglich sein wird, einen sehr schwach gekerbten Rand von einem ungekerbten Principiell zu unterscheiden . . . Wichtiger ist schon in systematischer Hinsicht das Vorkommen von Nebenzähnchen, weil ihre Ausbildung eine längere Differenzierung voraussetzt.— O. Jaekel, Die eocãnen Selachier vom Monte Bolca (1894), p. 164.

updated 3/2/05

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