A chordate is a deuterostomal bilaterian animal belonging to the phylum Chordata. All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics (synapomorphies) that distinguish them from other taxa. These five synapomorphies are a notochord, a hollow dorsal nerve cord, an endostyle or thyroid, pharyngeal slits, and a post-anal tail.
Vetulicolia is a group of bilaterian marine animals encompassing several extinct species from the Cambrian, and possibly Ediacaran, periods. As of 2023, the majority of workers favor placing Vetulicolians in the stem group of the Chordata, but some continue to favor a more crownward placement as a sister group to the Tunicata. It was initially erected as a monophyletic clade with the rank of phylum in 2001, with subsequent work supporting its monophyly. However, more recent research suggests that vetulicolians may be paraphyletic and form a basal evolutionary grade of stem chordates.
Yunnanozoon lividum is an extinct species of bilaterian animal from the Lower Cambrian Chengjiang biota of Yunnan province, China. Its affinities have been long the subject of controversy.
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.
Didazoon haoae is an extinct species of vetulicolid vetulicolian described by Shu, et al. based on fossils found in the Qiongzhusi (Chiungchussu) Formation, Yu'anshan Member, Lower Cambrian, in the Dabanqiao area (Kunming), about 60 km northwest of Chengjiang, China.
Pomatrum is an extinct vetulicolian, the senior synonym of Xidazoon; the latter taxon was described by Shu, et al. (1999) based on fossils found in the Qiongzhusi (Chiungchussu) Formation, Yu'anshan Member, Lower Cambrian, Haikou, (Kunming), about 50 km west of Chengjiang, China.
Vetulicolidae is a vetulicolian family from the Cambrian Stage 3 Maotianshan Shale and Sirius Passet Lagerstätte that consists of Vetulicola, Beidazoon, and Ooedigera. It is distinguished from the Didazoonidae by a harder body wall and the lack of an oral disc.
Didazoonidae is a vetulicolian family within the order Vetulicolata. It is charaterized by a relatively thin-walled, non-biomineralized body and a large, round anterior opening surrounded by an oral disc. It may be paraphyletic, even if the phylum Vetulicolia is monophyletic.
Ambulacraria, or Coelomopora, is a clade of invertebrate phyla that includes echinoderms and hemichordates; a member of this group is called an ambulacrarian. Phylogenetic analysis suggests the echinoderms and hemichordates separated around 533 million years ago. The Ambulacraria are part of the deuterostomes, a clade that also includes the many Chordata, and the few extinct species belonging to the Vetulicolia.
Deuterostomes are bilaterian animals of the superphylum Deuterostomia, typically characterized by their anus forming before the mouth during embryonic development. Deuterostomia is further divided into four phyla: Chordata, Echinodermata, Hemichordata, and the extinct Vetulicolia known from Cambrian fossils. The extinct clade Cambroernida is thought to be a member of Deuterostomia.
Banffozoa is an extinct class of bilaterians. Most workers place it in the Vetulicolia, but the protostome-like features of some members have motivated ongoing debate. Banffozoa consists of the order Banffiata as well as a dwarf "Form A" that has not been formally described or named. Skeemella has been placed incertae sedis in this class, but has more recently been placed with the Banffiidae. Banffozoa may be paraphyletic even if Vetulicolia is monophyletic.
Cotyledion tylodes is an extinct, stalked filter-feeder known from the Chengjiang lagerstatten. The living animal reached a couple of centimetres in height, and bore a loose scleritome of ovoid sclerites. Its interpretation has been controversial, but it is currently thought to be a member of the Entoprocta stem group.
Nesonektris aldridgei is an extinct vetulicolian from the Late Botomian-aged Emu Bay Shale Lagerstätte in Kangaroo Island, Australia. So far, it is the fourth described vetulicolian that is not restricted to the Maotianshan Shales.
Saccorhytus is an extinct genus of animal possibly belonging to the superphylum Ecdysozoa, and it is represented by a single species, Saccorhytus coronarius. The organism lived approximately 540 million years ago in the beginning of the Cambrian period. Initially proposed as a deuterostome, which would have made it the oldest known species of this superphylum, it has since been determined to belong to a protostome group called the ecdysozoans.
Beidazoon venustum is a marine deuterostome from the group Vetulicolia. It originates from the lower Cambrian Chengjiang biota of Yunnan Province, China, and was discovered in 2005. It is known as the smallest described vetulicolian, and for its surface being covered in many small nodes.
Vetulocystis is an extinct genus type genus of the family Vetulocystidae. It was found in the Maotianshan Shales, which date to roughly 518 mya.
Dianchicystis is an extinct genus of vetulocystid deuterostome. It was found in Jianshan, China, near Haikou, in the Cambrian Qiongzhusi Formation.
Shenzianyuloma is an extinct genus of vetulicolian represented by a single species, Shenzianyuloma yunnanense, from the Maotianshan Shale during Stage 3 of the Cambrian period. It is notable for having a compact body shape akin to that of an angelfish. It's exact phylogenetic position is unclear, and it was not included in a 2024 phylogenetic analysis of vetulicolians.
Heteromorphus is an extinct genus of banffiid from the lower Cambrian Chengjiang lagerstatte. It contains one broadly accepted species, Heteromorphus confusus, as well as a proposed junior synonym, Heteromorphus longicaudatus that may prove to be a separate species as additional specimens are examined. A much smaller species labeled "Form A" is allied with Heteromorphus at the class level but has not been formally described or assigned to Heteromorphus itself.
Thylacocercus is a genus of vetulocystid from the Wheeler Shale of Utah that is tentatively placed withini the family Vetulocystidae. Its discovery extended the temporal range of vetulocystids from the Lower Cambrian Stage 3 to the Middle Cambrian Stage 5 (Drumian), and the geographic range from South China to Laurentia.
