''Didazoon haoae'' is an extinct species of vetulicolid

vetulicolia 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 ...

n described by Shu, et al. based on fossils found in the Qiongzhusi (Chiungchussu) Formation, Yu'anshan Member (Eoredlichia zone),

Lower Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovici ...

, in the Dabanqiao area (

Kunming Kunming is the capital and largest city of the province of Yunnan in China. The political, economic, communications and cultural centre of the province, Kunming is also the seat of the provincial government. During World War II, Kunming was a Ch ...

), about 60 km northwest of Chengjiang,

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

Etymology

"Dida" abbreviates (in Chinese) the China University of Geosciences.

Description

The fossils show that the body of the animal was covered in a thin, flexible

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

. The

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

part of the body was divided into six segments, with fairly broad membranes separating the segments, and the posterior part of the body was divided into seven segments. The constriction between the anterior and posterior parts of the animal shows creasing, and the authors hypothesize that it was quite flexible. The fossils are interpreted as showing a large anterior opening, presumably a mouth, a spacious anterior cavity, an

alimentary canal The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...

, possibly voluminous in the anterior section, and a narrow

intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. T ...

in the posterior section, straight or coiled (in one specimen). There are five structures on each side of the anterior portion that the authors interpret as

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

. Narrow strands towards the

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

margins, sometimes branched, may represent

vascular tissue Vascular tissue is a complex transporting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. T ...

. The authors also identify a dark strand on the lower interior surface of the anterior section, which they speculate is an

endostyle The endostyle is an organ found in invertebrate chordate species of tunicates, lancelets, and in the larval stage of vertebrate lampreys. It assists in filter-feeding. It has evolved into the thyroid in vertebrate chordates. Since the endo ...

Taxonomy

''Didazoon'' is the type genus of the Didazoonidae, which one 2024 study has found to be a paraphyletic grade of the vetulicolians closest to crownward

chordates A chordate ( ) is a 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 ot ...

as shown in this simplified cladogram, which labels Vetulicolidae based on a 2018 phylogeny and Didazoonidae based on the

Paleobiology Database The Paleobiology Database (PBDB) is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database originated in the NCEAS-funded Phanerozoic Marine Pale ...

: An earlier study in 2014 place vetulicolians as the sister-group to tunicates, but was unable to resolve any relationships among vetulicolians as a group:

References

Works cited

* * * * {{Taxonbar, from=Q3707018 Animals described in 2001 Maotianshan shales fossils Monotypic vertebrate genera Prehistoric vertebrate genera Vetulicolia

Etymology

Description

Taxonomy

See also

References

Works cited