| Xianguangia Temporal range: Cambrian Stage 3, | |
|---|---|
 | |
| Fossil of Xianguangia sinica | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Stem group: | Ctenophora |
| Family: | † Dinomischidae |
| Genus: | † Xianguangia |
| Species: | †X. sinica |
| Binomial name | |
| †Xianguangia sinica Chen & Erdtmann, 1991 | |
Xianguangia is a soft-bodied sea anemone-like fossil animal from the Chengjiang Biota of China. [2]
Xianguangia sinica has a cylindrical body with a whorl of nearly 16 tentacles around the oral disc, similar to the modern anthozoans. The tentacles are feather-like with dense pinnules on both sides of the axis which would have been well adapted to filter feeding. A bowl-shaped attachment disc at the basal part might commonly have been buried in the sediment to allow its sedentary strategy on the sea floor. The body above the pedal disc is broad and cylindrical and may correspond to the internal gastrovascular cavity. It displays several distinct longitudinal grooves and ridges on the surface, indicating possible mesenteries. [3] However, its phylogenetic affinity has long been questioned; [3] it has even been alleged to be related to members of the Ediacara biota. [4] Studies from the late 2010s onwards argued that it was likely to be member of the stem-group of Ctenophora (comb jellies), related to taxa like Dinomischus and Siphusauctum. [5] [6]
The fossils, found in Yunnan province, China, were initially described as three distinct species, Xianguangia sinica, Chengjiangopenna wangii, and Galeaplumosus abilus, and then assembled into one proposed species, X. sinica, in 2017. [7] The animal was polyp-like, its gastric cavity divided by septa; it had a second body cavity in its holdfast, and densely-plumed feather-like tentacles, implying that it was a suspension feeder. Early cnidarians were probably also benthic suspension feeders, unlike later mainly predatory cnidarians. [7]
Ctenophora comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming, and they are the largest animals to swim with the help of cilia.
The Maotianshan Shales (帽天山页岩) are a series of Early Cambrian sedimentary deposits in the Chiungchussu Formation, famous for their Konservat Lagerstätten, deposits known for the exceptional preservation of fossilized organisms or traces. The Maotianshan Shales form one of some forty Cambrian fossil locations worldwide exhibiting exquisite preservation of rarely preserved, non-mineralized soft tissue, comparable to the fossils of the Burgess Shale of British Columbia, Canada. They take their name from Maotianshan Hill in Chengjiang County, Yunnan Province, China.
Vetulicola is an extinct genus of marine animal discovered from the Cambrian of China. It is the eponymous member of the enigmatic phylum Vetulicolia, which is of uncertain affinities but may belong to the deuterostomes. The name was derived from Vetulicola cuneata, the first species described by Hou Xian-guang in 1987 from the Lower Cambrian Chiungchussu Formation in Chengjiang, China.
Amplectobelua is an extinct genus of late Early Cambrian amplectobeluid radiodont, a group of stem arthropods that mostly lived as free-swimming predators during the first half of the Paleozoic Era.
Dinomischusis an extinct genus of stalked filter-feeding animals within the Cambrian period, with specimens known from the Burgess Shale and the Maotianshan Shales. While long of uncertain affinities, recent studies have suggested it to be a stem-group ctenophore.
Acanthomeridion is an extinct arthropod found in the Chengjiang fauna deposits of China. In 1997, it was placed in its own, monotypic family, Acanthomeridiidae. It is known from eight specimens, all found in China.
Facivermis is a genus of sessile lobopodian from the Lower Cambrian Maotianshan shales of China
Archaeopriapulida is a group of priapulid worms known from Cambrian lagerstätte. The group is closely related to, and very similar to, the modern Priapulids. It is unclear whether it is mono- or polyphyletic. Despite a remarkable morphological similarity to their modern cousins, they fall outside of the priapulid crown group, which is not unambiguously represented in the fossil record until the Carboniferous. In addition to well-preserved body fossils, remains of several archaeopriapulid taxa are known to have been preserved primarily as organic microfossils, such as isolated scalids and pharyngeal teeth. They are probably closely related or paraphyletic to the palaeoscolecids; the relationship between these basal worms is somewhat unresolved.
Vetulicola cuneata is a species of extinct animal from the Early Cambrian Chengjiang biota of China. It was described by Hou Xian-guang in 1987 from the Lower Cambrian Chiungchussu Formation, and became the first animal under an eponymous phylum Vetulicolia.
Eldoniids or eldonioids are an extinct clade of enigmatic disc-shaped animals which lived in the early to middle Paleozoic. They are characterized by their "medusoid" (jellyfish-shaped) bodies, with the form of a shallow dome opening below to an offset mouth supplemented by filamentous tentacles. Internally, they have a distinctive C-shaped cavity encompassing the gut, as well as hollow radial (radiating) structures arranged around a central ring canal. Most eldoniids are soft-bodied and can only be preserved in lagerstätten, but a few species may have hosted mineralized deposits. Historically, the affinities of eldoniids was enigmatic; recently, they been assessed as cambroernid deuterostomes. Their lifestyle is still an unresolved question; some authors reconstruct eldoniids as free-floating planktonic predators similar to jellyfish, while others argue that they were passive detritivores, embedded within the seabed for much of their life.
Eolympia is interpreted as an extinct monospecific genus of sea anemone or dinomischid ctenophore which existed in what is now Ningqiang, Shaanxi Province, China during the lower Cambrian period. Its fossils have been recovered from the Kuanchuanpu Formation. The pedicle is long, suggesting the animal engaged in sexual intercourse, though marked perforations imply that reproduction by transverse fission was also quite likely as a more primitive backup.
Siphusauctum is an extinct genus of filter-feeding animals that lived during the Middle Cambrian about 510 million years ago.
Vetulicola rectangulata is a species of extinct animal from the Early Cambrian of the Chengjiang biota of China. Regarded as a deuterostome, it has characteristic rectangular anterior body on which the posterior tail region is attached. It was described by Luo Huilin and Hu Shi-xue in 1999.
Archotuba is a genus of elongated conical tubes that were seemingly deposited by colonial organisms. Known from the Chengjiang, its biological affinity is uncertain; it somewhat resembles the tubes of the 'priapulid' Selkirkia, but a cnidarian affinity is also possible. In the absence of soft parts, there is insufficient data to confirm a biological affiliation.
Retifacies abnormalis is an extinct arthropod that lived in the lower Cambrian. Its fossil remains have been found in the Maotianshan Shales of Yunnan, China. It is a member of the Artiopoda, and closely related to Pygmaclypeatus.
Luolishania is an extinct genus of lobopodian panarthropod and known from the Lower Cambrian Chiungchussu Formation of the Chengjiang County, Yunnan Province, China. A monotypic genus, it contains one species Luolishania longicruris. It was discovered and described by Hou Xian-Guang and Chen Jun-Yuan in 1989. It is one of the superarmoured Cambrian lobopodians suspected to be either an intermediate form in the origin of velvet worms (Onychophora) or basal to at least Tardigrada and Arthropoda. It is the basis of the family name Luolishaniidae, which also include other related lobopods such as Acinocricus, Collinsium, Facivermis, and Ovatiovermis. Along with Microdictyon, it is the first lobopodian fossil discovered from China.
Lenisambulatrix is a genus of extinct worm belonging to the group Lobopodia and known from the Lower Cambrian Maotianshan shale of China. It is represented by a single species L. humboldti. The incomplete fossil was discovered and described by Qiang Ou and Georg Mayer in 2018. Due to its missing parts, its relationship with other lobopodians is not clear. It shares many structural features with another Cambrian lobopodian Diania cactiformis, a fossil of which was found alongside it.
Wufengella is a genus of extinct camenellan "tommotiid" that lived during the Early Cambrian. Described in 2022, the only species Wufengella bengtsonii was discovered from the Maotianshan Shales of Chiungchussu (Qiongzhusi) Formation in Yunnan, China. The fossil indicates that the animal was an armoured worm that close to the common ancestry of the phyla Phonorida, Brachiozoa and Bryozoa, which are collectively grouped into a clade called Lophophorata.
Nailiana elegans is a species of stem-Cnidarian from the Chengjiang biota of China that has a polypoidal body plan. The species was first described in 2021 from multiple solitary specimens from China, with some being preserved with Cambrian Lingulids that would suggest a lifestyle as a macrophagous predator from the Cambrian. Naliana probably represents one of the earliest evidence for a macrophagous predator within the fossil record, and, because of how the structure of food webs from the Cambrian were very poorly understood with most reconstructions of them being based upon the feeding interactions between Animal species or upon the gut-content of extremely well-preserved fossils, provides important insights and evidence for how complex the nature of early Cambrian food chains actually were.
Daihua sanqiong is a possible ancestor of comb jellies. It was a sessile relative to comb jellies. It had combs with cillia just like modern day comb jellies.
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