|Tree Shrew - not a primate|
|Colugo - also not a primate|
Instead of developing tool use, the strepsirrhines developed a useful modification of their lower incisors called the tooth comb, which is used in grooming their fur and also in gouging plant stems and tough-shelled fruits. Unlike the haplorrhines, they have a ‘wet’ nose like a dogs, which improves scent detection (smell is a more important sense than sight in a nocturnal animal).
Perhaps around the end-Cretaceous impact, the strepsirrhines in turn split into two branches. One became the lorises and galagos of mainland Africa and Asia, the other became ancestral to modern lemurs. It seems most likely that the cause of the split was the colonisation across the Mozambique Channel by the ancestral lemur in a single event, but it is possible the split occurred on the mainland and there were multiple colonisations by groups ancestral to the various families of lemurs found today. Unfortunately fossil evidence is rare for any primate, and there are no known fossil deposits from Madagascar for the key dates.
In the absence of fossil evidence, DNA analysis has come to the rescue, and the modern lemurs can be divided into five families, with an additional three families of recently extinct lemurs wiped out by humans in the last 1000 years or so.
1) Cheirogaleidae (mouse lemurs) – these are very galago-like and are the most conservative of the lemur families). Bristol has one species, and has bred them repeatedly
|Grey Mouse lemur|
|Sahamalaza Sportive Lemur|
8) Daubentoniidae – the Aye-Aye. Perhaps the most famous (certainly the weirdest-looking) of all lemurs, indeed of all primates, it is also the most evolutionarily distinct, with an estimated divergence time from the other lemur species suspiciously close to the end-Cretaceous impact, though what the significance of that is I have no idea. Bristol is one of the few zoos in the world to hold the species, and we have bred them on two occasions.
(images from wikipedia, Bristol Zoo website)