Tarsiers

Today their range is limited to some rain forests of Southeast Asian islands of Malaysia, Indonesia, the Philippines and nearby smaller islands.

The family name reflects one of their physical traits, long tarsals, or foot bones. The large feet, in conjunction with their above average ratio of leg size to arm size, provides them with an ability to leap from tree to tree for both defensive purposes and their search for prey, insects.

Their over-sized eyes, an attention getter, are a common trait for nocturnal primates, shared, for example, by species in the New World night monkey or owl monkey genus, Aotus.

Categorizing tarsiers has proved to be a challenging task for most primate specialists. Historically, primate taxonomy has followed a top down structure, with physical similarities used as the primary grouping tool.

Early taxonomic efforts, for example, tended to lump them in with lemurs, albeit with noted differences. The 1894 volume of The Royal Natural History: Mammals noted:

"It is, therefore, clear that the tarsier differs very markedly from ordinary lemurs; and, if our observations made under the head of fossil lemurs have been understood, it will be apparent that in this respect the tarsier is what zoologists term a more generalised form than the true lemurs, and that it closely resembles the extinct types. Indeed the series of teeth in the extinct microchoere are expressed by the same formula as the one denoting those of the tarsier. We may, therefore, venture to conclude that this animal shows in its teeth signs of affinity with the extinct European lemurs, which have been lost in the true lemurs and their allies. In regard to the elongation of the bones of the upper half of the ankle, the tarsier is, however, evidently a specialised, or highly modified creature; and it is probable that the same structural peculiarity did not exist in the Eocene lemurs."

Today's primate taxonomists still follows a a top down structure, with primates fitting into one of two infraorders, Strepsirrhini and Haplorrhini.

By most accounts, many tarsier physiological and DNA features show them more closely related with the apes and monkeys, rather than the lemurs. Therefore, they are currently placed as a separate and distinct family withing the Haplorrhini, although with further research that categorization is subject to change.

Tasrier research continues to improve and over the past two decades, the number of species and subspecies continues to grow and change. In 2010, the IUCN recognized eight species, two of which, the Sangihe Tarsier (Tarsius sangirensis) and the Peleng Tarsier (tarsius pelengensis), were listed as endangered.

© 2010 Patricia A. Michaels.