Isurid teeth are often an impressive component of Cenozoic marine sediments. If the teeth of the hastalis-type are deemed to be makos, then identifying them to genus is an easy task. However, if those hastalis-type teeth are ascribed to Cosmopolitodus GLIKMAN, 1964, then distinguishing the makos from the ancestral Great whites is important. Many of the ambiguities may be removed if the extant isurids are employed for comparative purposes.

In addition to the noise created by cosmopolitodid teeth, two distinct Isurus species teeth are often present, those of the Shortfin [I. oxyrinchus RAFINESQUE, 1810 or desori (SISMONDA, 1849)] and Longfin [I. paucus GUITART MANDAY, 1966 or retroflexus (AGASSIZ, 1843)] makos. Depending on the author, the fossil teeth may be assigned to a different species than their modern counterparts.¹ For that reason, fossil dentitions will eventually be incorporated into this presentation.

It is difficult to determine the path this slideshow will follow, but it will be mako-centric and attempt to consolidate discussion on this topic.

Mako Dentition

In general terms, the mako has a grasping-cutting dentition made-up of teeth with a smooth (and generally complete) cutting-edge and (usually) lacking lateral cusplets. Three teeth emanate from an anterior hollow (both upper and lower) in all species. The first and second are 'awl-like' in design and serve a grasping function. A latero-posterior hollow produces the teeth usually referred to as laterals and posteriors. The first five (or so) are often called laterals and the remainder posteriors. Unlike the sand tigers, the gradient heterodonty of the lateral teeth makes ascribing them to a particular file-group a subjective judgment. In this discussion, teeth produced by the anterior hollow will be referred to as anterior teeth and the others, laterals.²

Acknowledgements

As with most elasmo.com projects, this slide-show required the contributions of multiple interested persons. These include: Gordon Hubbell, Pat & Ken Young, Bill Heim, Anthony Chappell, Henry Mollet and those referenced authors that have contributed to this topic.

Footnotes

1. Purdy et al (2001) grouped Lee Creek teeth of the Longfin-design with hastalis.

2. Certain authors refer to reduced teeth from the mesial position of the anterior hollow as symphyseals or parasymphyseals. Some authors (usually the same) prefer to use the term 'Intermediate' for teeth emanating from a distal position of the anterior hollow. It is this author's opinion that only anterior teeth are produced by the anterior hollow - symphyseals are not present and only the 'bar' or diastema between the hollows can produce intermediate teeth. Steve Cunningham discussed this matter in detail in the Carcharias Dentition slide show.