| 词条 | Zhongjianichthys |
| 释义 |
| fossil_range = {{fossil range|535|525}} | image = Zhongjianichthys rostratus.jpg | image_caption = Artist's reconstruction | genus = Zhongjianichthys | parent_authority = Shu, 2003 | species = rostratus | authority = 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 characteristicsThe 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. EcologyZhongjianichthys 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]LocationsZhongjianichthys specimens have been found in the early Cambrian Maotianshan shales of China.[1]References1. ^1 2 {{Cite web|url=http://palaeos.com/vertebrates/vertebrata/craniata.html|title=Palaeos Vertebrates : Vertebrata : Craniata|website=palaeos.com|access-date=2018-02-04}} {{Taxonbar|from=Q1467281}}{{Paleo-jawless-fish-stub}}{{cambrian-animal-stub}} 4 : Maotianshan shales fossils|Prehistoric jawless fish genera|Cambrian fish|Fossil taxa described in 2003 |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。