Stirtonia is named after the scientist who first discovered it, Ruben Arthur Stirton. The two species,S. tatcoensis and S. victoriae, are named after the locations in which they were found:S. tatacoensis gets its name from the Tatacoa desert; andS. victoriae gets its name from the village “La Victoria” near its discovery site.[6][7][8]
The genus is the largest primate found at La Venta,[9] with estimated body masses ofS. tatacoensis at 5,513 grams (12.154 lb) and ofS. victoriae at 10 kilograms (22 lb).[10]Stirtonia tatacoensis andS. victoriae are known by several teeth, a mandible and a maxilla that closely resemble, and are almost indistinguishable from, the livingAlouatta.[11]
A lower mandible fossil ofS. tatacoensis was discovered during fieldwork between 1944 and 1949,[13] in theHonda Group, that has been dated to theLaventan, about 13 Ma.
Upper jaws and other cranial material of the large primateStirtonia victoriae from the Perico Member of the La Dorada Formation, Honda Group were discovered in 1985 and 1986. Based on stratigraphic position, more than 300 metres (980 ft) below theStirtonia tatacoensistype locality, this was the oldest primate material known until 1987 from Colombia.[14]
The Honda Group, and more precisely the "Monkey Beds", are the richest site forfossil primates in South America.[16] It has been argued that the monkeys of the Honda Group were living in habitat that was in contact with theAmazon andOrinoco Basins, and that La Venta itself was probably seasonally dry forest.[17] From the same level as whereStirtonia tatacoensis has been found, also fossils ofAotus dindensis,Micodon,Mohanamico,Saimiri annectens,Saimiri fieldsi andCebupithecia have been uncovered.[18][19][20]Stirtonia reinforced the notion that leaf-eating was anenduring and essential aspect of the howler monkey's ecophylogenetic biology.[21]
McKenna, Malcolm C.; Bell, Susan K. (1997),Classification of Mammals Above the Species Level, New York:Columbia University Press, pp. 1–631,ISBN0-231-11013-8
Rosenberger, Alfred L.; Cooke, Siobhán B.; Halenar, Lauren B.; Tejedor, Marcelo F.;Hartwig, Walter C.; Novo, Nelson M.; Muñoz Saba, Yaneth (2015),Howler Monkeys, Developments in Primatology: Progress and Prospects - Chapter 2 Fossil Alouattines and the Origins of Alouatta: Craniodental Diversity and Interrelationships,Springer Science+Business Media New York, pp. 21–54
