Dvulikiaspis

Dvulikiaspis; Temporal range: Lochkovian,
	Interpretive drawing of PIN 1271/2, the holotype of Dvulikiaspis menneri
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Clade:	Dekatriata
Order:	†Chasmataspidida
Family:	†Diploaspididae
Genus:	†Dvulikiaspis; Marshall et al., 2014
Type species
	†Dvulikiaspis menneri; Novojilov, 1959

Dvulikiaspis is a genus of chasmataspidid, a group of extinct aquatic arthropods. Fossils of the single and type species, D. menneri, have been discovered in deposits of the Early Devonian period (Lochkovian epoch) in the Krasnoyarsk Krai, Siberia, Russia. The name of the genus is composed by the Russian word двуликий (dvulikij), meaning "two-faced", and the Ancient Greek word ἀσπίς (aspis), meaning "shield". The species name honors the discoverer of the holotype of Dvulikiaspis, Vladimir Vasilyevich Menner.

Its prosoma (head) was subquadrate (almost square) to parabolic (nearly U-shaped), with (bean-shaped) to subovate (nearly oval) eyes and surrounded by a marginal rim. The abdomen was composed by a fused buckler and a postabdomen that occupied most of the body length, while the telson (the posteriormost division of the body) was small and semicircular in shape. The appendages (limbs) were uniform. The sixth and last pair of them had a paddle-like shape and was placed in front of the midpoint of the prosoma. The largest specimen was 2.64 centimetres (1.04 inches) long.

The first fossil was described in 1959 as a new species of the eurypterid Stylonurus, while the other two were discovered in 1974. It would not be until 2014 when D. menneri was recognized as a chasmataspidid genus, being placed in the family Diploaspididae. However, Dvulikiaspis was similar to Loganamaraspis and especially Hoplitaspis, with which it could form a new separate family of chasmataspidids.