A New Species of Yunnanozoan with Implications for Deuterostome Evolution

  title={A New Species of Yunnanozoan with Implications for Deuterostome Evolution},
  author={De-gan Shu and Simon Conway Morris and Z. F. Zhang and J N Liu and Jian Han and Ling Chen and X. Zhang and Kinya Yasui and Yong Li},
  pages={1380 - 1384}
Yunnanozoans are a distinctive clade of Lower Cambrian metazoans. Although widely accepted as deuterostomes, their exact placement within this superphylum is controversial. Here we describe a new species of Haikouella (H. jianshanensis) from the Chengjiang Lagerstätte (Yunnan, China) with exceptional preservation of a number of features. These include external gills, which suggest that the origin of the pharyngeal clefts was independent of the gills. The diagnostic branchial arches of… 

Response to Comment on "A New Species of Yunnanozoan with Implications for Deuterostome Evolution"

A new species of Haikouella is described from the Chengjiang Lagerstätte with exceptional preservation of a number of features, which suggest that the origin of the pharyngeal clefts was independent of the gills and the diagnostic branchial arches of chordates may, therefore, be composite structures.

Ancestral echinoderms from the Chengjiang deposits of China

The vetulocystids appear to have similarities not only to the vetulicolians but also to the homalozoans, a bizarre group of primitive echinoderms whose phylogenetic position has been highly controversial.


Abstract:  A new metazoan, Skeemella clavula gen. et sp. nov., is described from the Middle Cambrian Pierson Cove Formation of the Drum Mountains, Utah, USA. Skeemella is similar to vetulicolians,

Comment on "A New Species of Yunnanozoan with Implications for Deuterostome Evolution"

The authors interpreted this soft-bodied animal as a stem-group deuterostome, and the descriptions of new Haikouella fossils with great interest confirmed this interpretation.

New data on the palaeobiology of the enigmatic yunnanozoans from the Chengjiang Biota, Lower Cambrian, China

This analysis reveals new details of the putative pharyngeal pores of Yunnanozoon lividum, and although there are similarities with the gill slits of deuterostomes, the question of their homology remains moot.

The earliest history of the deuterostomes: the importance of the Chengjiang Fossil-Lagerstätte

The known diversity of Chengjiang deuterostomes are reviewed and it is argued that the vetulicolians and yunnanozoans represent very primitive deuterOSTomes, as well as new data to indicate that the yunncozoans are unlikely to be any sort of chordate.

Gill rays of primitive vertebrate Yunnanozoon from Early Cambrian: a first record

New findings of the distinct gill rays of Yunnanozoon lividum are described based on new well-preserved material collected from the Lower Cambrian Maotianshan Shale in Xiaolantian of Yunnan Province, China.


It is not possible on current evidence to reach an unequivocal conclusion regarding the phylogenetic position of the vetulicolians, but one possibility is that they are a sister group of arthropods that lost limbs but gained gill structures analogous to those of deuterostomes, but several features remain unexplained by this model.

Tentaculate Fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) Interpreted as Primitive Deuterostomes

The evidence is suggested that the evidence is more consistent with the ambulacraria being primitive deuterostomes, with specific comparisons being made to the pterobranch hemichordates and pre-radial echinoderms.

Primitive deuterostomes from the Chengjiang Lagerstätte (Lower Cambrian, China)

Several features of the Chengjiang fossil-Lagerstätte suggest that this group can throw light on an early stage of deuterostome diversification, and provide evidence for a new group of metazoans, the vetulicolians.

A possible Early Cambrian chordate

The first chordate recorded from the Early Cambrian is the ceph-alochordate Yunnanozoon lividum from the 525 million-year-old Chengjiang fauna and predicts that other chordate clades (tunicates and craniates) had evolved by the Late Atdabanian, in the main burst of the Cambrian Explosion.

Lower Cambrian vertebrates from south China

The discovery of two distinct types of agnathan from the Lower Cambrian Chengjiang fossil-Lagerstätte imply that the first agnathans may have evolved in the earliest Cambrian, with the chordates arising from more primitive deuterostomes in Ediacaran times (latest Neoproterozoic, ∼555 Myr BP), if not earlier.

Reinterpretation of Yunnanozoon as the earliest known hemichordate

Yunnanozoon is reinterpreted here as the earliest known hemichordate, and its typical tripartite body plan is broadly consistent with that of living balanoglossid hemichor-dates (enteropneusts).

Yunnanozoon and the ancestry of chordates

The oldest known chordate, Yunnanozoon lividum Hou et al. 1991, from the Chengiang Lagerstatte of Yunnan shows several features in its anatomy that had not been expected to occur at this stage of

Head and backbone of the Early Cambrian vertebrate Haikouichthys

Phylogenetic analysis indicates that Haikouichthys somewhat resembles the ammocoete larva of modern lampreys, this is because of shared general craniate characters; adult lampreys and hagfishes (the cyclostomes if monophyletic) are probably derived in many respects.

Evolution of the chordate body plan: new insights from phylogenetic analyses of deuterostome phyla.

The nesting of the pterobranchs within the enteropneusts dramatically alters the view of the evolution of the chordate body plan and suggests that the ancestral deuterostome more closely resembled a mobile worm-like enteropNEust than a sessile colonial pterOBranch.

Composition and preservation of the Chengjiang fauna –a Lower Cambrian soft‐bodied biota

The Lower Cambrian Chengjiang fauna is reviewed and shown to be closely comparable with the younger Burgess Shale fauna. but with various differences in detail. A diverse group of more or less

Paired gill slits in a fossil with a calcite skeleton

Using computer X-ray microtomography, the anatomy of Jaekelocarpus is described in greater detail than formerly possible, evidence of paired gill slits internally is revealed and its phylogenetic position within the deuterostomes is suggested.

Decay of Branchiostoma: implications for soft‐tissue preservation in conodonts and other primitive chordates

Decay experiments on the cephalochordate Branchiostoma lanceolatum (‘amphioxus’) demonstrate that the most decay resistant structures are the notochord sheath and the cartilaginous rods which support the gill bars, and cast light on the interpretation of a number of primitive fossil chordates.