The Lower Cambrian Phlogites Luo & Hu re-considered

Alcheringa: An Australasian Journal of Palaeontology, 2006

Palaeontology, 2014

Palaeontology, 2014

"Diploblastic eumetazoans of the phylum Cnidaria originated during the Neoproterozoic Era, possibly during the Cryogenian Period. The oldest known fossil cnidarians occur in strata of Ediacaran age and consist of polypoid forms that were either nonbiomineralizing or weakly so. The oldest possible anthozoans, including the genus Ramitubus, may be related to tabulate corals and occur in the Doushantuo Lagerstatte (upper Doushantuo Formation, South China), the age of which is poorly constrained (approximately 585 Ma?). Conulariid scyphozoans may first appear as early as 635–577 Ma (Lantian Formation, South China). A definite conulariid, most similar to Palaeozoic species assigned to the genus Paraconularia, occurs in association with the possible scyphozoan, Corumbella werneri, in the latest Ediacaran (c. 543 Ma) Tamengo Formation of Brazil. Basal Cambrian (c. 540 Ma) phosphorites in the upper Kuanchuanpu Formation (South China) yield solitary polyps of the oldest probable anthozoan (Eolympia pediculata), which appears to have been a stem hexacorallian. This same formation contains fossils interpreted by some authors as pentaradial cubozoan polyps; however, both the oldest known cubozoans and the oldest hydrozoans, all medusae, may actually occur in the Cambrian (Series 3, c. 505 Ma) Marjum Formation (Utah, USA). Although these recently published palaeontological data tend to corroborate the hypothesis that Cnidaria has a relatively deep Neoproterozoic history, the timing of major internal branching events remains poorly constrained, with, for example, the results of some molecular clock analyses indicating that the two cnidarian subphyla (Anthozoaria and Medusozoa) may have originated as many as one billion years ago. Further progress towards elucidating the evolution and early fossil record of cnidarians may accrue from: (1) an intensive search for phosphatized soft parts in possible anthozoans from the Ediacaran Doushantuo Formation; (2) an expanded search for Ediacaran conulariids; and (3) additional detailed analyses of the taphonomy and preservation of Ediacaran and Cambrian cnidarians, including possible pentaradial cubozoan polyps from the Fortunian upper Kuanchuanpu Formation."

Biology …, 2011

Palaeontologia Electronica, 2024

Enteropneusts (acorn worms) are hemichordates, the sister group to echinoderms. Together they form the clade Ambulacraria, which is closely related to chordates. All three groups appear in the lower Cambrian, but their interrelationships remain problematic, which impedes the understanding of early deuterostome evolution. Enteropneusts are also extremely rare in the fossil record, only a few species are known from Lagerstätten-type deposits. Here, we describe the earliest known enteropneust, Cambrobranchus pelagobenthos gen. et sp. nov. based on soft-bodied specimens, including tornaria larvae and juveniles, from the lower Cambrian (Epoch 2, Stage 3) Haiyan Lagerstätte, Chengjiang biota, of China. The enteropneust larvae and post-metamorphic juveniles are the first reported in the fossil record and provide direct evidence for a pelago-benthic lifestyle in a Cambrian deuterostome animal, bolstering the hypothesis that an indirect development is primitive to the enteropneusts and maybe the hemichordates or whole of Ambulacraria.

2002

The evolution of the earliest metazoans has been the subject of debate in recent years, particularly regarding the speed of change and the diversity of general body plans Bergström 1995, Fortey et al. 1996). Argu-ments have centered on how representative the fossil record is and the usefulness of techniques such as cladism and specially molecular analysis (Bergström 1986) whose varied results have shown it to be premature (Hou and Rev.

Chinese Science Bulletin, 2006

Facivermis yunnanicus , from the Early Cambrian Chengjiang Lagerstätte, a worm-like fossil with 5 pairs of tentacles and a perceived shrunken end, has been regarded as related to polychaetes, later it has been variously interpreted as lobopods, Pentastoma and lophophorates. Newly discovered complete specimens by the ELI field team show that the taxon has, in addition to the 5 pairs of appendages, a pear-shaped trunk end bearing two or three circles of hooks. Accordingly, based on these important morphological characters, reconsideration of its affinities is provided and the taxonomy is remedied herein. Because the five pairs of appendages of Facivermis yunnanicus resemble the appendages of the fore-trunk of lobopod Miraluolishania , it seems that they are homologous structures. Therefore, the affinities of Facivermis are regarded here as being close to the lobopods, in addition, the lobe-like appendages of Facivermis are very crucial to exploring the origin of the appendages of lobopods and arthropods.

Evolution & Development, 2025

Cambrian Lagerstätten yield exceptionally preserved fossils that have greatly improved our understanding of the origin and evolution of animal groups. Brachiopoda, a phylum of bivalved marine invertebrates nested firmly within the lophotrochozoan protostomes, are widely recovered in such Lagerstätten. The marginal chitinous setae (or chaetae) of brachiopods are the most commonly described soft tissue and have been interpreted as performing a defensive and/or sensory role. Despite their relatively common appearance in Cambrian Lagerstätten, the origin, function, and evolution of setae in the Brachiopoda is poorly known. Here, we document exquisitely preserved setal structures from South China and Laurentia paleocontinents giving new insights into their formation, microstructure and preservation mode. New setae typically make their appearance within the follicle of a neighbouring older seta and then branches off laterally forming its own follicle. Setal microstructure is likely to be composed of many canals, highly comparable to setae of their recent counterparts. Moreover, setae recovered from these palaeo-continents present different preservation: aside from the normal preservation of iron oxides and carbonaceous ingredients, some compositions of calcium are also detected in this originally chitinous organization. Investigating the evolutionary origins of chitinous setae, a specialized type found notably in lophotrochozoans such as brachiopods and annelids, reveals its presence in early Cambrian stem groups. This character likely serves as a morphological synapomorphy in lophotrochozoan evolution. However, the dearth of morpho-ultrastructure and comparative studies in Cambrian fossils presents a challenge in fully understanding this evolutionary development.

2017