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artwork 11" x 14"
Superclass: Agnatha (Jawless Vertebrates)
Species: Haikouichthys ercaicunensis Luo et al.
Haikouichthys ercaicunensis is an extinct, primitive, jawless fish dating back to 530 million years ago, at the dawn of the Cambrian Period, a time when life was exploding with new and wondrous complex organisms. The oceans covered 85% of the Earth and most of the land was tied up in the giant continent Gondwana, which straddled the southern hemisphere from the South Pole to the Equator. South China, separated from North China, was located on the equator, just north of Gondwana, and was mostly submerged beneath the ocean. Haikouichthys lived in the warm, shallow waters created by this meeting of sea and land.
Haikouichthys was small, about 25 mm (1 inch) long, and had a dorsal fin that ran the length of its body then merged with the tail fin. The fish had a narrow ventral fin fold. The fish had a cranium, a brain, eyes, 6 to 9 gills and gill bars, and V-shaped muscle blocks. Most notably, Haikouichthys had a notochord with vertebra-like elements, making it one of the earliest vertebrates to evolve and therefore ancestor to everyone who has a backbone.
Haikouichthys' fossils were discovered in 1984 in Chiengjiang, near Kunming (capital city of Yunnan Province), in southwest China. These fossils were among hundreds of fossils of soft-bodied species found in this area. These finds have been of great importance in refining our understanding of the story of life on Earth. Before Haikouichthys' fossils were found, scientists estimated that the first vertebrates had evolved during the Ordovician Period, some 50 million years after Haikouichthys lived. Two other species of fish in the the same Family (Myllokunmingiidae) were discovered in this same region and come from the same time period: Myllokunmingia fengjaoa Shu, Zhong, and Han and Zhongjianichthys rostratus Shu. Similar and closely related living fish include hagfishes and lampreys.
Benton M. 1993. The Rise of the Fishes. In: Gould SJ, editor. The Book of Life. New York (NY): W. W. Norton & Company. P. 65-78.
Guerrero AG, Frances P. 2009. Prehistoric Life. New York (NY): Dorling Kindersley Limited.
Hellman GS, Collette BB, Facey DE, Bowen BW. 2016. The Diversity of the Fishes. 2nd ed. United Kingdom: Wiley-Blackwell.
Shu DG, Luo HL, Morris SC, Zhang XL, Hu SX, Chen L, Han J, Zhu M, Li Y, Chen LZ. 1999. Lower Cambrian Vertebrates from South China. Nature 402:42-46.