In Depth
One of the monkey lemurs from Madagascar, Hadropithecus is often described as being similar to its relative Archaeolemur in behaviour and lifestyle. Hadropithecus was a powerfully built lemur that seems to have been best adapted to a cursorial life on the ground. Lemurs as we know them today usually have long arms and hands for reaching out and grasping around tree branches, but the arms and hands of Hadropithecus were proportionately much shorter than these arboreal forms. These shorter limbs would have been more efficient for ground locomotion, but they may have meant that Hadropithecus spent most if not all of its time on the ground. On the ground, Hadropithecus would have been able to scavenge seeds that had fallen from higher growing plant. These seeds would have likely been covered in tough husks to protect them, but this does not seem to have been a problem for Hadropithecus since the robust teeth would have easily sheared through the husks to reveal the highly nutritious contents. Hadropithecus has also been considered to have been a grazer, but a 2008 study by Ryan et al suggests a greater reliance upon eating hard foods like seeds.
The dental formula of Hadropithecus reads as 2.1.3.3 for the upper jaw and 1.1.3.3 for the lower jaw. For anyone who is not familiar with how to read a dental formula, the numbers correspond to the numbers of specific kinds of teeth in one half of the jaw. The first number is for incisors, the second for canines, third for premolars and fourth for molars. So with this in mind Hadropithecus had two incisors, one canine, three premolars and three molars in one half of the upper jaw, and one incisor, one canine, three premolars and three molars in the one half of the lower jaw. To find the total number of teeth in the mouth of Hadropithecus you just have to add up these two formulas and then multiply the result by two. This means that one half of the upper jaw had nine teeth, one half of the lower jaw had eight teeth and these combine to make seventeen teeth. You then multiply this figure by two, which is akin to adding the second halves of the upper and lower jaws to give you a total of thirty four teeth in the mouth. This example explains Hadropithecus, but it’s worthwhile knowing how to read dental formulas since they form a very big part in the study of prehistoric mammals.
Like with much of the Madagascan fauna of the Holocene, and particularly ground lemurs, Hadropithecus seems to have gone extinct not long after the first humans colonised Madagascar. Aside from competition from new animals being introduced to the land, habitat loss caused by humans would have also contributed to the demise of lemurs like Hadropithecus.
Further Reading
- A reconstruction of the Vienna skull of Hadropithecus stenognathus, T. M. Ryan, D. A. Burney, L. R. Godfrey, U. B. Gohlich, W. L. Jungers, N. Vasey, Ramilisonina, A. Walker & G. W. Weber - 2008. - New discoveries of skeletal elements of Hadropithecus stenognathus from Andrahomana Cave, southeastern Madagascar, L. R. Godfrey, W. L. Jungers, D. A. Burney, N. Vasey, Ramilisonina, W. Wheeler, P. Lemelin, L. J. Shapiro, G. T. Schwatrz, S. J. King, M. F. Ramarolahy, L. L. Raharivony & G. F. N. Randria - 2006.
