Primates come in a huge range of sizes from the great apes all the way down to a tiny little species known as Madame Berthe’s mouse lemur.

Sadly, however, the smallest side of that spectrum may be a little bit bigger now because, according to a study publishing the results of an attempt to determine how many (if any) of them were still living, none have been seen since around 2018. The team of conservationists who wrote the study said:

“Our monthly population monitoring failed to record any sightings or trappings of M. berthae in an 80 [hectare] study area since 2018, even though they used to be common there. Although it is impossible to prove that M. berthae has actually gone extinct while there is still forest left, these data are alarming and suggest that it may now be the first lemur species to have gone extinct in the 21st century.”

Of course, all hope is not lost. Trying to find these tiny little primates is not easy. To start with, their bodies measure just 9-9.5 centimeters (3.5-3.7 inches). If you add on their 12-14 centimeter (4.7-5.5 inch) tails they get a lot longer, but certainly not much easier to spot.

In addition to being so small, the Madame Berthe’s mouse lemur spends most of its life up in the trees of Madagascar’s southwestern Menabe region. They were only just identified as a unique species in 1992, so humans didn’t even know they existed until recently, and now we very well may have driven them to extinction.

These tiny lemurs only lived in one very small part of Madagascar because the majority of their diet consisted of a sugary substance that comes from the nymphs of the planthopper Flatida coccinea. The sweet substance is called honeydew, but it is not the fruit. Instead, these insects produce it as a waste product after feeding on one specific type of liana, which is a woody vine found only in this region.

To put it simply, this little lemur was highly specialized to live in this area, and unfortunately, their habitat has been devastated by deforestation to make room for agriculture, illegal logging, and a variety of other issues in the region.

While the conservationists are still looking for signs that the lemurs have survived, they are at the very least, critically endangered. These little lemurs would spend most of their life on their own, sometimes coming together in small groups to sleep, only to go their separate ways when awake.

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