Zhongjianichthys

Zhongjianichthys Temporal range: 535–525 Ma PreЄ Є O S D C P T J K Pg N
Artist's reconstruction
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Superclass:	Agnatha
Order:	Myllokunmingiida
Family:	Myllokunmingiidae
Genus:	Zhongjianichthys
Species:	Z. rostratus
Binomial name
Zhongjianichthys rostratus Shu, 2003

Zhongjianichthys rostratus is an extinct basal chordate that lived in the Cambrian period, approximately 530 million years ago. It is sometimes regarded as an early fish, and therefore as one of the first vertebrates.

Physical characteristics

The eyes are located behind the antero-dorsal lobe and the mouth apparently did not have a jaw. It lacked scales, and had a thick skin. We know it had a thicker skin than other chordates at that time because, unlike Myllokunmingia, no impressions of its myomeres have been found. The ventral fin is low in height, and runs much of the body's length.^[1]

Although Zhonjianichthys appears more advanced than its relatives due to the back-positioned eyes and the thicker skin, this may be convergent evolution and it may not, therefore, be particularly closely related to the ancestors of modern chordates.

Ecology

Zhongjianichthys' reduced fins may indicate that it was mainly bottom-dwelling and did not swim much. This could have been a factor in its evolution of thicker skin, as protection from predators.^[1]

Locations

Zhongjianichthys specimens have been found in the early Cambrian Maotianshan shales of China.^[1]

References