The missing fossils argument; new fossils support 'gap' (Introduction)

by David Turell , Saturday, May 04, 2024, 17:15 (203 days ago) @ David Turell

New Cambrian forms, some more complex than their current forms:

https://evolutionnews.org/2024/05/fossil-friday-kinorhyncha-yet-another-animal-body-pla...

"This Fossil Friday we will look at an obscure group of animals from a clade of molting invertebrate animals called Ecdysozoa that include the roundworm phyla (Nematoda, Nematomorpha, Priapulida, Loricifera, and Kinorhyncha) as well as tardigrades, velvet worms (Onychophora), extinct lobopods, and arthropods. Almost all of these ecdysozoan phyla have been recorded from the Lower Cambrian and thus clearly originated with the burst of biological creativity in the Cambrian Explosion, which brought forth all the different animal body plans.

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"Indeed, apart from some dubious trace fossils and microfossils from the terminal Ediacaran ...unequivocal body fossils of the ecdysozoan phyla (i.e., Priapulida and Loricifera) are first appearing in the Early to Middle Cambrian. The extinct Palaeoscolecida (Early Cambrian – Silurian) are considered to be either stem nematomorphs or rather stem priapulids. Maas et al. (2010) described a possible stem Nematoida (Nematoda+Nematomorpha) from the Middle Cambrian of Australia, but its closer affinities remain unknown. A notable gap in our knowledge of ecdysozoan history was the phylum Kinorhyncha, which until recently had no known fossil record at all. These animals are small marine invertebrates that are also called mud dragons because of their spiny body.

"Hardly a decade ago, Chinese scientists described “three dimensionally phosphatized worm-like fossils from the early Cambrian rocks, approximately 535 million years old, in northern Sichuan and southern Shaanxi provinces” of South China. They were interpreted as early kinorhynchs and therefore named Eokinorhynchus rarus (featured above). The 2 mm long animals only differed from their living relatives in having more body segments and more distinct spines. In other words: the earliest kinorhynchs were more complex than modern ones. So much for the evolutionary narrative from simple to complex. (my bold)

"Five years later, Shao et al. (2020) described Zhongpingscolex qinensis from the Early Cambrian (Fortunian Stage) of South China. Their phylogenetic analysis resolved this new taxon as closest relative (sister group) of Eokinorhynchus in the stem group of Kinorhyncha.The authors did not mention three undescribed taxa of fossil kinorynchs with up to 40 mm length from the Middle Cambrian Qingjiang biota in China.

"Based on these findings we can safely count Kinorhyncha among the large number of animal phyla that originated abruptly in the Cambrian Explosion. The more we learn about the fossil record the more the Cambrian Explosion is confirmed as a key event in the history of life, which defies Darwinian explanations.'

Comment: Note my bold. we generally assume life evolves to the more complex, but some forms are seen to devolve to simpler type. This article is part of a continuing event, the discovery of new fossils in China whose shale beds ae rich in fossils. These new fossils constantly enforce the 'gap' as a real explosion of new forms without predecessors.