Asilisaurus (/ɑːˌsiːliːˈsɔːrəs/ ah-SEE-lee-SOR-əs); from Swahili, asili ("ancestor" or "foundation"), and Greek, σαυρος (sauros, "lizard") is an extinct genus of silesaurid archosaur.

It had several unique features compared to its close relatives, such as a lack of teeth at the front of the premaxilla and a lower jaw which was not only toothless at the tip, but also downturned.

[4][2][3] Asilisaurus was a lightly built animal with a fairly long neck (by early archosaur standards), a short snout tipped with a beak, and slender limbs.

[4] The ~3 meter upper length estimate is based on NHMUK R16303, an incomplete silesaurid femur found in the Manda Beds.

Uncertainty over the stratigraphic position of the specimen and a lack of unambiguously Asilisaurus-like traits means that it is not certain that NHMUK R16303 belongs to Asilisaurus.

The premaxilla is large and primarily toothless, with a sharp lower edge converging towards a pointed front tip.

This is also the case with the palatal process of the maxilla, which has a flat surface separated from the rest of the bone via a ridge and pit.

The front tip of the jugal is pointed, wedging between a wide lower branch of the lacrimal and a presumably sloping rear portion of the maxilla.

In addition, advanced silesaurids have a longitudinal groove at the lower edge of the inner portion of the dentary, while that of Asilisaurus is positioned higher.

Asilisaurus has fewer teeth in the dentary (8-10) than other silesaurids, and the tooth row occupies a smaller portion of the bone than its relatives.

The rear of the lower jaw is similar to other silesaurids, with a long retroarticular process and weakly defined surangular ridge.

However, the postzygapophyses of a few vertebrae do have small projections identified as epipophyses, which are present in aphanosaurs and dinosaurs but not advanced silesaurids.

Several aspects of the humerus, such as the small deltopectoral crest connected to the humeral head by a thick ridge, do not resemble the situation in dinosaurs.

These include a groove on the top of the femoral head, a facies articularis antitrochanterica, three equally well-developed proximal tubera, and an anterior trochanter and trochanteric shelf.

Much of the lower portion of the femur is also weakly developed, with the exception of a groove on the rear edge of the bone, which is extended up the shaft to the same extent as most other silesaurids.

The tibia is also par for the course for dinosauriforms, with a straight cnemial crest, two equally sized proximal condyles, and a lateral groove in the distal portion.

Asilisaurus retains a "primitive" crurotarsal ("crocodile-normal") ankle characterized by a convex-concave interaction between the astragalus and calcaneum.

[2][3] Evidence for a beak at the tip of the snout and peg-like teeth further back support the idea that Asilisaurus was an omnivore or herbivore.

[2][4] The conical shape of the teeth shares some similarities with piscivorous reptiles such as spinosaurids and crocodilians, leading to the possibility that fish were part of its diet.

[10] There is only a weak relationship between skeletal maturity and size, as some small "robust" femora are more well-developed than some large "slender" ones.

Large "slender" femora can be explained as coming from young Asilisaurus which were able to increase in size by taking advantage of plentiful resources, but had not yet attained skeletal maturity.

Small "robust" femora are a result of the opposite circumstance, belonging to mature Asilisaurus which grew up in more impoverished environments.

This type of "developmental plasticity" has previously been proposed for Plateosaurus, some "pelycosaurs" (basal synapsids), and observed in modern Alligator mississippiensis.

The large amount of variability in Asilisaurus' sequence of muscle scar development is likely a matter of individual variation.

It is hypothesized that a lack of LAGs is not indicative that all the specimens died within a year, as the estimated growth rate is not fast enough to achieve skeletal maturity within that time period.

Instead, Asilisaurus may have had a constant and moderately high growth rate (though slower than dinosaurs), which was not impeded by any seasonal interruptions.