Jaekel (1895) erected this genus for the teeth described by Agassiz (1843) as ? Lamna hopei and L. verticalis. In 1988, Ward synonymized these teeth under the name Carcharias hopei. In North America at least, the Ward assignment has been generally followed (Ward & Weist 1991, Kent 1994, Purdy 1998, Kent 1999, elasmo.com 1999-2005). In 2005, Cappetta & Nolf (C&N) published an extensive review of Palaeogene sand tigers of Europe. In that paper, the authors resurrected Hypotodus, rejected C. hopei (sensu Ward 1988), and assigned many (but not all) of the Agassiz specimens to Hypotodus verticalis (following Nolf 1988). Rather than three upper anteriors, there were only two -- a significant observation and a reasonable basis for a genus other than Carcharias. These tooth-set observations are in line with Cunningham (unpublished) and appear valid. Whether the specific name should be hopei or verticalis is arguable. Elasmo.com will follow C&N in this matter, but it must be pointed out that some teeth formerly ascribed to C. hopei in various collections may not be H. verticalis.

Using C&N as a guide and Cunningham (2000) methodology, the accompanying tooth-set was constructed. As can be noted, not only has an upper A1 tooth-position been lost (or at least been replaced by a stunted tooth, the existance of which is currently undetermined) but the awl-like Carcharias tooth-design has been replaced by more mesio-distally expanded teeth. As Ward (pers com 2005) notes, the typical sand tiger (sensu Carcharias) tearing-dentition is becoming more cutting/clutching-like in design. Not seen in this tooth-set image is the erect shape (when viewed laterally) of these smooth-crowned teeth.

Typically, H. verticalis teeth have a single, 'primary cusp'-directed cusplet on each shoulder. Infrequently, on both sides of the Atlantic, there may be a second cusp on each side as seen in Winkler's (1874b) "Otodus" vincenti subsequently synonymized by Leriche (1905 & 06) with "Lamna" verticalis.

Selected References (additional in Bibliography)

Agassiz, L. J. R. 1833-1844. Recherches sur les poissons fossiles. Text (5 vols; I., xlix+188 pp., II xii+310+366 pp., III viii+390 pp., IV xvi+296 pp., V xii+122+160 pp.) and Atlas (5 vols; I 10 pl., II., 149 pl., III 83 pl., IV, 61 pl., V, 91 pl.). Neuchâtel.
Cappetta, H & Nolf, D, 2005. Revision de quelques Odontaspidae (Neoselachii: Lamniformes) du Paleocene et de l'Eocene du Bassin de la mer du Nord Bulletin de l'institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre 75:237-266.
Cunningham, S. B. 2000. A comparison of isolated teeth of early Eocene Striatolamia macrota (Chondrichthyes, Lamniformes), with those of a Recent sand shark, Carcharias taurus. Tertiary Research 20(1-4): 17-31.
Jaekel, O., 1895. Unter-Tertiäre Selachier aus Südrussland. Mémoires du Comité Géologique de Saint-Pétersbourg, 9: 19-35.
Kent, B. 1994. Fossil Sharks of the Chesapeake Region. Egan Rees & Boyer, Maryland, 146 pp.
Kent, B. 1999. Sharks from the Fisher/Sullivan Site. In: Weems, R. & Grimsley, G., Early Eocene Vertebrates and Plants from the Fisher/Sullivan Site (Nanjemoy Formation) Stafford County, Virginia. Virginia Division of Mineral Resources, Pub 152: 11-37.
Leriche, M. 1905. Les Poissons Paléocènes de la Belgique. Mémoires du Musée Royale d'Histoire Naturelle de Belgique. Bruxelles. 33: 49-228.
Leriche, M. 1906. Contribution à l'étude des poissons fossiles du Nord de la France et des régions voisines. Mémoires de la Société géologique du Nord, 5: 1-430.
Nolf, D., 1988. Fossiles de Belgique. Dents de requins et de raies du Tertiaire de la Belgique. Institut royal des Sciences naturelles de Belgique, 184 pp.
Purdy, R. 1998. Chondrichthyan Fishes from the Paleocene of South Carolina. In: Paleobiology of the Williamsburg Formation (Black Mingo Group; Paleocene) of South Carolina, U.S.A., Albert Sanders ed. Transactions of Amer. Philo. Scty., vol 8 (4), pp 122-146.
Ward, D. J. 1988. Hypotodus verticalis (Agassiz, 1843), Hypotodus robustus (Leriche, 1921) and Hypotodus heinzelini (Casier, 1967), Chondrichthyes, Lamniformes, Junior Synonyms of Carcharias hopei (Agassiz, 1843). Tertiary Research, 10: 1-12.
Winkler, T.C., 1874b. Deuxième mémoire sur des dents de poissons fossiles du terrain bruxellien. In: Archives du Musée Teyler, 1878; vol. IV (fasc. 1, 1876), pp 16-48; Extrait, 10 pages. Les Héritiers Loosjes, Haarlem, Belgium.