Anatosuchus
Anatosuchus ("duck crocodile", the name from the Latin anas ("duck") and the Greek souchos ("crocodile"), for the broad, duck-like snout) is an extinct genus of notosuchian crocodylomorph discovered in Gadoufaoua, Niger, and described by a team of palaeontologists led by the American Paul Sereno in 2003, in the Journal of Vertebrate Paleontology.[1] Its duck-like snout coincidentally makes it resemble a crocoduck, an imagined hybrid animal with the head of a crocodile and the body of a duck.[2][3]
The type species of Anatosuchus is A. minor, in reference to its small body size. The holotype material (MNN GDF603), is a nearly complete skull with articulated lower jaws, belonging to a juvenile. It was discovered from the upper portion of the Elrhaz Formation and lower portion of Echkar Formation, indicating an Early Cretaceous (Late Aptian or Early Albian) age.[1] Another specimen was found later (MNN GAD17) belonging to an adult, which had both the skull and much of the postcranial skeleton. Differences in the skull indicate that the unusual broad, flattened shape developed as the animal grew older.[4]
The premaxillae are broad and flat, and form a line straight across the front of Anatosuchus's snout; each holds six recurved teeth which point backwards into the mouth. The internarial processes of the premaxillae taper steeply up towards the projecting nasals; they begin as very wide, meaning that the external nares are dorsoventrally compressed. The premaxillae also form the floor of the narial passages, including a small flange which causes the nares to point up and out somewhat. This gives Anatosuchus a visible projecting nose on the front of its broad snout. The smooth narial fossae are located just behind these, and help to give the snout its broad flattened look.[4]
The maxillae are, by quite a long way, the largest and most expansive bones in the skull; each holds nineteen small recurved teeth. They have a narrow alveolar margin at the edge of their broad expanse, giving the head of Anatosuchus a rather rectangular appearance, and broad rami that extend above and below the antorbital opening. The upper of these rami form a long suture with the nasal, and then meet the prefrontal and lacrimal directly above the antorbital fenestra. The alveolar margin is vertically oriented, but runs anteroposteriorly rather than transversely as that of the premaxilla does. The maxilla is quite highly textured with pits and neurovascular canals, although far less than the nasal, frontal and parietal bones in particular.[4]
The maxillae also form much of the palate, particularly at the anterior section of the palate; the palatine bones form almost all the remainder. The median one-third (measured transversely from left to right) is arched dorsally, making the buccal cavity larger, whereas the two lateral thirds by this measure are horizontal. There is a slit-shaped foramen on each maxilla on the palate. The very posterior section is formed by the pterygoid and ectopterygoid; these also form the projecting posteroventral mandibular rami. The choanae are as far back as possible without contacting the suborbital fenestrae; there is a thin choanal septum between them where they emerge in the pterygoids.[4]
