First appearing in the Late Jurassic, these small, featherless runners have a fragmentary and poorly-known early history. After the low-slung, Late Jurassic †Elaphrosaurus of Africa (and possibly North America as well), noasaurids are only known from the Southern Hemisphere, with Cretaceous forms including †Noasaurus and †Ligabueino from Argentina. These predators are best known for their slashing, sickle claws, which were thought to have evolved independently from the deinonychosaurs, but presumably used for the same purpose. However, it has been found that noasaurids actually carried these claws on their hands. †Velocisaurus, another noasaurid from the same time and place as Noasaurus, also represents the earliest record of the characteristic noasaurid feet, in which the first toe is lost, the second and fourth short and narrow and the third long and strong. Aside from a single bizarre skull from Madagascar belonging to the cretaceous Masiakasaurus knopfleri, and a few fragments from India, there is little else known of the pre-Cenozoic history of the clade Noasauridae.
The oldest complete noasaurid skeleton comes from the Eocene of Argentina. These remains represent an animal that must have been quite similar to the living cain (Cain cursor), which inhabits modern Madagascar. Noasaurids seem to have vanished from South America when a meteorite struck 3.3 million years ago, though the paleontology of Spec is still in its infancy and precludes certainty in such conclusions. In any case there are no longer any noasaurs in South America; they have been replaced by cazadins.
Cain (Cain cursor)
The only long-distance pursuit hunter of Madagascar, which is otherwise ruled by ambushing crocodiles and stefs, is the 3.5 m long cain (Cain cursor). It is the main predator of hypsies and alvies, which it pursues over long distances in the grassland much like a cheetah in Home-Earth. These predators leap onto their prey in the manner of a deinonychosaur or rahonavid and kills them with its strongly curved sickle claws. Its arms are short, but strong, armed with respectable talons, and the cain uses these appendages to get a secure hold on the prey. The feet are extremely specialized for running – the third toe is long and robust, the fourth toe is thin and short, while the second toe, which carries the sickle claw, is raised above the ground. This case of convergent evolution is quite surprising, particularly as most Mesozoic noasaurids carried such claws on their hands, rather than their feet.
Also see: The Mark of Cain
The ancestry of the kagrus is not clear, for although they must have been in Africa already in the Cretaceous, the earliest known kagru fossils are the distinctive Late Eocene teeth from Egypt called †Protokagru aegyptiacum. It seems like the early kagrus profited from the decline of the African alverezsaurs and became the most important termite eaters of Africa and southern Asia (which they reached in the Miocene), although kagru diversity is quite low (and apparently has always been so). The two known species of modern kagru are very distinctive in body type, having become beautifully specialized to their ant-eating lifestyle.
Kagru (Kagru kagru)
While kagrus retain the long legs and tails of their remote cain-like ancestors, their forelimbs have grown large thumb claws, with which they claw at the walls of termite mounds, and their heads have changed enormously, their snouts elongated by 6-8 long, conical teeth. These teeth grow forward nearly horizontally from their roots to form a single enamel-hardened pick, which, driven by muscles anchored at the base of the kagru's neck, can be driven into a termite mound with smashing force.
Once the outer shell of the insects' fortress is breached, the dinosaur extends a long, sticky tongue into the passages of the mound, extracting workers and eating them before the soldiers can mount a defense.
Striated Kagru (Kagru longidentatum)
The striated kagru is distinguished from its close cousin, the common kagru by the number and size of its teeth, its slightly smaller size, and its relatively longer and more powerful arms. This kagru is a forest-dweller, feeding upon the nests of ants and other colonial insects.
These species of Nosauridae have specialized to an aquatic livestyle, like the duckgongs, potamoceratopsids and nodopotamids else where in the world. However, only one species in known to exist. The murcosaur.
Murcosaur (Mucrodontosaurus piscivorus)
Mucrodontosaurus piscivorus, endemic to Madagascar, is a species of highly specialized piscivores. Distantly related to the other abelisauroids of mainland Africa, mucrosaurs are generally small, with broad, flexible tails, webbed feet, and tooth-filled jaws. Aside from the Cain, they are seemingly Madagascar's last noasaurids. Though it is unknown what their relationship is to ancient species, it seems to fill the same niche of a fish-hunting theropod as its ancient relation Masiakasaurus once did in Madagascar, a niche that the extinct spinosaurids filled elsewhere during their reign.
,=K. kagru (Hacktooth/common kagru) ,=Kagru=| ,=Kagruinae=| `=K. longidentatum (Striated kagru) | | =Noasauridae=| `=†Protokagru aegyptiacum | `=Cain cursor (Cain)