Merriam (1898) assigned to Tamaulipas four Life-zones. There were:
Transitional on the highest elevations of the Sierra Madre; Upper
Austral at lower elevations on the Sierra Madre; Lower Austral over
most of the state; and Tropical in the coastal areas.
Dice (1943) outlined Biotic Provinces on a map of North America and in
the northern part of Tamaulipas showed two Biotic Provinces, Tamaulipan
and Potosian. He did not show the southeastern limits of the Chihuahuan
Biotic Province nor any of the limits of the Veracruzian Biotic
Province and in text mentioned nothing about the limits of these two
provinces with reference to Tamaulipas. Later, Goldman and Moore (1946)
divided Tamaulipas in three Biotic Provinces: Tamaulipas, Sierra Madre,
and Veracruz. Still later (1949), Smith published a map of Mexican
Biotic Provinces based on the herpetofauna of the Republic. He divided
Tamaulipas among four Provinces. Two were Nearctic (Austro-oriental and
Tamaulipan) and the other two were Neotropical (Veracruzian and
Cordoban).
Leopold (1950 and 1959) recognized five principal vegetational types in
Tamaulipas as follows: Mesquite-grassland; Pine-oak Forest; Thorn
Forest; Tropical Deciduous Forest; and Desert.
For dealing with the mammals of Tamaulipas in the following accounts
the four Biotic Provinces (Tamaulipan, Potosian, Veracruzian, and
Chihuahuan) of Dice are the most useful. For dealing with types of
vegetation in the accounts that follow, Leopold's (1950) system is
employed although reference is made to other associations and
formations that have been reported in Tamaulipas.