The flat-tail horned lizard is named for United States Army Colonel George A. M'Call,[4] who collected the first specimen in California in the 19th century.

[3] In addition, the dark midline helps to disrupt the outline of the lizard, resembling the thin shadows of plant stems in its windswept sand habitat.

[6] In 1982, the US Fish and Wildlife Service declared P. mcallii as a Candidate 2 Category for the list of threatened and endangered species due to concerns over potential threats to their habitat which could further diminish the population.

The purpose of this work was to determine the local distribution and relative abundance of P. mcallii, to correlate these parameters with various habitat attributes, and to gather information on the structure of the populations and mobility and food habits of individual lizards.

The species was most abundant in places with the Western whiptail (Cnemidophorus tigris), nests of the black harvester ant (Messor pergandei), galleta grass (Hilaria rigida) and sandy soils.