Morohasaurus

Morohasaurus is an extinct genus of cf. monstersaurian squamates know from a single left dentary from the Early Cretaceous (?Albian) Ohyamashimo Formation of the Sasayama Group in Tamba City, Hyogo Prefecture, Japan.^[1] The type and only species is Morohasaurus kamitakiensis.

Morohasaurus Temporal range: Albian? 100 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Clade:	Monstersauria
Genus:	†Morohasaurus Ikeda et al., 2021
Type species
†Morohasaurus kamitakiensis Ikeda et al., 2021

As of 2021, Ikeda et al. place this taxon a conferatur within Monstersauria based on general synapomorphies but without performing a phylogenetic analysis. The unique characters described in the paper to distinguish Morohasaurus kamitakiensis as a valid species include "the sinuous posteroventral rim of the dentary with a large U-shaped upper notch and small V-shaped lower notch, posteroventral corner of intramandibular septum with a weakly pointed eminence projecting posteriorly, and unicuspid, curved trenchant teeth with distinct blade-like carinae on their mesial and distal sides without grooves or serrations." If its presumed affinities are correct, Morohasaurus represents the oldest known monstersaurian to date.^[1]

References

1. Ikeda, T.; Ota, H.; Tanaka, T.; Ikuno, K.; Kubota, K.; Tanaka, K.; Saegusa, H. (2021). "A fossil Monstersauria (Squamata: Anguimorpha) from the Lower Cretaceous Ohyamashimo Formation of the Sasayama Group in Tamba City, Hyogo Prefecture, Japan". Cretaceous Research. 130: Article 105063. doi:10.1016/j.cretres.2021.105063. S2CID 239230916.