Alemoatherium

Alemoatherium; Temporal range: Late Carnian PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Diagram of the lower jaw in medial view
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Clade:	Therapsida
Clade:	Cynodontia
Clade:	Prozostrodontia
Genus:	†Alemoatherium; Martinelli et al., 2017
Type species
	Alemoatherium huebneri; Martinelli et al., 2017

Alemoatherium is an

postcanine teeth show many similarities with those of dromatheriids, an obscure group of early prozostrodontians.^[1]

Description

The

dentary is similar in shape to that of many other prozostrodontians, with an overall slender form that abruptly changes angle near the front of the jaw. This distinct change in angle separates the dentary into two main regions, the horizontal ramus behind the level of the first postcanine tooth, and the upwards-tilted anterodorsal process in front of the first postcanine. Seen in medial (inside) view, the dentary has a faint groove along the tooth row and a much more prominent Meckelian groove parallel to its lower edge. A short and smoothly rounded ridge is visible in medial view close to the front of the dentary. This corresponds to the unfused symphysis, where the left and right jaws connect to each other at the chin.^[1]

Dentition

Alemoatherium has five incisors, one canine, and at least seven postcanines on its lower jaw. Though none of the incisors are fully preserved, the largest would have been the first incisor (i1), indicated by an alveolus (tooth socket) which was strongly procumbent (oriented forwards) and circular in cross section. The second incisor (i2) was smaller and strongly worn on the labial (cheek) side. The third, fourth, and fifth incisors (i3-i5) are similar but smaller still. The single canine tooth (c1) is quite small, with a straight distal (rear) edge and no apparent serrations. The first postcanine tooth (pc1) is similar to the canine but larger, with a tiny second cusp behind the main cusp. The second postcanine (pc2) is not preserved but it would have been slightly larger than pc1.^[1]

The third postcanine (pc3) has four main cusps: the large main cusp (a), preceded by a small cusp (b), and followed by two more small cusps (c and d). This tooth is a fairly typical cynodont

root, the predecessor condition to a bifurcated root. The even larger fifth postcanine (pc5) is similar to the fourth, though cusp b is taller, cusp d curves further, and two cingular cusps are positioned below cusp b rather than just one. The sixth postcanine (pc6) is similar to its predecessors and is the largest preserved tooth in the jaw, though it has only one cingular cusp. The seventh postcanine (pc7) is not preserved, but its alveolus indicates that it was around the size of pc3.^[1]

Classification

The unfused mandibular symphysis and constricted roots of the lower postcanines support the placement of Alemoatherium within

brasilodontids (overall jaw and tooth shape). However, all of these taxa also possess traits contradicting the remains of Alemoatherium. The teeth of Alemoatherium share many similarities to those of dromatheriids, a poorly-known group of cynodonts found in North America, Europe, and India. Its dentary was also very similar to those of dromatheriids such as Microconodon and Dromatherium, supporting their connection further.^[1]

Below is a

phylogenetic analysis (excluding Santacruzgnathus, Microconodon, and Charruodon).^[1]

Alemoatherium