r/AIDKE

One of my favorite extinct animals! They're super underrated in my opinion

Credit to Jake Guzman

Large rodent carrying leaves and branches back and forth

And a Masked Crab (Corystes Cassivelaunus)

Such a beautiful chunky borb

These snakes make up the genus Langaha, with three species total, all endemic to the island of Madagascar. 

The “noses” of each species do look different — the nose of the Ambilobe leaf-nosed snake (pictured top right) looks like the end of a broken branch, for instance. But the most striking variance exists between the sexes. Male Malagasy leaf-nosed snakes possess straighter, pointier protrusions, while those of females are frillier and more leaf-like. 

Why the sexual dimorphism? There are a few theories.

One is that these differing protrusions create different search images (the mental templates predators use to recognise their prey), making it harder for hawks, mongooses, and fossas to memorise exactly how the snakes look, thus making it harder to find them.

Another theory revolves around niche-differentiation and partitioning. The male, with his straighter nose, mimics straight twigs or thin, hanging vines. He can catch the smaller, faster lizards that frequent the thin outer branches. The female, with her frayed nose, mimics rough bark, lichen, diverging buds, or a snapped branch. She hides among the textured branches of the interior to ambush larger prey. The two sexes “partition” out the tree, so they can live in the same territory without starving each other out. 

The final theory is an expansion of the last one: rather than just partitioning niches, the two sexes partition entire habitats, in a way. These snakes live both in Madagascar's lush rainforests and scrubby dry forests — with the male more camouflaged in the former, and the female in the latter. And whichever sex is at an advantage in any given habitat, is the one that actively seeks out a mate. This allows the species to survive and breed across varied habitats. Or so the theory goes.

It’s always difficult to find definitive answers for evolutionary questions. All of these theories may be correct or none of them may be quite right. Naturally, it’s quite hard to study species that evolved not to be seen.

Learn more about these leaf-nosed snakes, and other cryptic species, here!

The silvery marmoset (Mico argentatus) is a small, New World monkey from the eastern Amazon rainforest in Brazil.

They reach a size of 18 to 28 cm (7.1 to 11.0 in) and weigh from 300 to 400 g (11 to 14 oz). Their lifespan is roughly 16 years.

Silvery marmosets are diurnal and arboreal. Their fingers end in claws rather than nails (as is true of all marmosets) using their claws to climb trees and gouge gum out of tree bark. They spend the night in tree hollows or in very close vegetation. They live together in small groups and mark their territory with scent glands, driving out intruders by shouting or by facial expressions

The diet of the silvery marmosets predominantly consists of tree sap. To a lesser extent, they also eat bird eggs, fruit, insects, and small vertebrates.

In the wild, silvery marmosets live in groups of 4–15 individuals. The core of each group is a dominant male-female pair and their offspring

The International Union for Conservation of Nature lists silvery marmosets* *as Least Concern (IUCN, 2015), appearing on the IUCN Red List of Threatened Species.

Knew about their giant Aussie and European distant cousins, but never knew about this scamp. I'm especially fond of the pink bill and striated feathers on the back.