SYSTEMATICS AND DENTITION

Class CHONDRICHTHYES Huxley, 1880
Subclass ELASMOBRANCHII Bonaparte, 1838
Subcohort NEOSELACHII Compagno, 1977
Superorder GALEOMORPHII Compagno, 1973
Order CARCHARHINIFORMES Compagno, 1973
Family HEMIGALEIDAE Haase, 1879
Genus HEMIPRISTIS Agassiz, 1843
Species H. CURVATUS Dames, 1883 (Eocene)
Species H. SERRA Agassiz, 1843, (Oligocene – Pleistocene)
Species H. ELONGATA Klunzinger, 1871 (Recent)

Synonyms for Hemipristis elongata include Dirrhizodon elongatus (Klunzinger, 1871), Carcharias ellioti (Day 1878), Hemipristis pingali (Setna and Sarangdhar 1946), Paragaleus acutiventris (Chu 1960), Heterogaleus ghardaqensis (Gohar and Mazhar 1964), and Hemipristis elongatus (Compagno 1984) (gender mismatch). This instance is somewhat unusual because a valid fossil name (Hemipristis) has historical precedence over a valid extant name (Dirrhizodon).

Fossil and Recent teeth of many sharks of the Order Carcharhiniformes are difficult to identify at a species level (Naylor and Marcus 1994). Hemipristis serra upper teeth, however, are easily identifiable by anyone at all familiar with shark teeth (Cappetta 1987, p. 118, Hulbert 2001, p. 90). Baranes and Ben-Tuvia (1979) give a typical dental formula for the extant species as but without identifying the numbers of anterior, lateral, and posterior teeth. On one side of the upper jaw there are two reduced-size teeth adjacent to the midline which are designated as parasymphyseals, followed by two full-sized teeth designated as anteriors, followed by six to seven laterals, and ending with three to four posteriors. The lateral teeth are all rather similar, and it is difficult to assign a precise jaw position to fossil lateral teeth. A Hemipristis serra upper lateral tooth (from the Middle Miocene Pungo River Formation) which almost perfectly fits Cappetta's (1987) Hemipristis description is pictured on the left in Figure 1. The distal side is to the left.

The specimens used in this study were specifically chosen to be upper lateral teeth. The sacrifice that was made (in order to obtain a relatively large dataset) was the inability to test if jaw position was significant in the measurements that were taken. A better choice would have been to use only the first upper anterior teeth (see Figure 1). This tooth is unique (one on each side of the jaw) and easily identified. Unfortunately, there were statistically insignificant numbers of this tooth in the available samples.