A. Order--Cetacea.

The scientific order Cetacea includes all whales. This order is further divided into three suborders.

1. Odontoceti (toothed whales).

The toothed whales include dolphins, porpoises, beluga whales, beaked whales, and sperm whales.

2. Mysticeti (baleen whales).

The baleen whales include blue whales, gray whales, and right whales.

3. Archaeoceti.

The archaeocetes are an extinct group of whales, of which only fossils remain (Barnes, 1990).

B. Family--Delphinidae.

Dolphins and their immediate kin are included in the scientific family Delphinidae. This family is represented by about 30 species, including common dolphins, pilot whales, killer whales, and false killer whales.

C. Genus, species--Tursiops truncatus.

Although biochemical evidence supports the existence of several geographical races, most scientists currently recognize only one species of bottlenose dolphin (Klinowska, 1991).

D. Fossil Record.

1. Many scientists believe that early whales arose 50 million years ago from (now extinct) primitive mammals that ventured back into the sea (Barnes, 1990). Two small rod-shaped pelvic bones, buried deep in the body muscle of toothed whales, may be remnants of the hind limbs of these primitive mammals (Rommel, 1990).
2. Modern forms of both odontocetes and mysticetes appear in the fossil record five to seven million years ago.
3. The genus Tursiops first appears in the fossil record about five million years ago (Barnes, 1990).