Megazostrodon

Megazostrodon is an extinct genus of basal mammal that lived during the Late Jurassic and Early Cretaceous periods, approximately 150 to 140 million years ago. Its fossils have been discovered in southern Africa. Megazostrodon is significant for being one of the earliest known mammals, providing crucial insights into the origins and evolution of the mammalian lineage.

The animal was small, estimated to be about 10-15 centimeters long, and likely resembled a shrew or a small rodent. Its diet is believed to have consisted of insects and other small invertebrates, which it would have hunted at night. Megazostrodon possessed primitive mammalian characteristics, including a fused jaw bone and a dentary-squamosal jaw articulation, a defining feature of mammals. Its teeth were sharp and adapted for shearing, suggesting a carnivorous or insectivorous diet.

Evidence suggests that Megazostrodon, like many early mammals, may have been nocturnal, an adaptation that would have allowed it to avoid predation by larger dinosaurs that dominated the terrestrial ecosystems of the time. The discovery of Megazostrodon and other early mammals helps paleontologists understand the diversification of mammals during the Mesozoic Era, a period when they coexisted with dinosaurs but remained relatively small and ecologically subordinate. Its existence demonstrates that mammals were already established and evolving independently long before the extinction of the non-avian dinosaurs.