| Hadrynichorde Temporal range: | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | incertae sedis |
| Genus: | Hadrynichorde Hofmann et al. 2008 |
| Type species | |
| Hadrynichorde catalinensis | |
Hadrynichorde is a frondose organism from the Ediacaran period (635-541 mya) discovered in Newfoundland, Canada. It is a sessile, benthic marine organism. [1] resembling modern sea whips. [2]
Hadrynichorde specimens are described as filamentous, string-like fossils with basal discs. [1] [3] [4] [5] These basal discs are ellipsoid or ovoid in shape and are interpreted as holdfasts, [1] though some hypothesize that the discs are unrelated to the fronds. [4] The string-like portion of Hadrynichorde is described as curvilinear, either uniform or with a slight taper. The specimens found are uncoiled, but display bends and kinks indicating draping over other organisms. The strings resemble burrows, but due to the tapering nature and terminal disc, this is unlikely. [1] Some specimens have swelling along their length, resembling a knotted string. [2]
The orientation of strings of Hadrynichorde is parallel to some Charnia fronds on same bedding plane, indicating a tethered or sessile lifestyle. Specimens are estimated to reach up to a meter above the sea floor. This interpretation is consistent with the interpretation of a similar organism, Hadryniscala, as Laminaria-like kelp fragment. Hadrynichorde is hypothesized to be a photosynthetic organism. [1]
There is some discussion that Hadrynichorde may be part of a larger body fossil. [5]
Hadrynichorde fossils have been discovered in Newfoundland as molds and negative epireliefs, [1] and similar but unidentified organisms have been found in Australia and Russia as negative and positive epireliefs, and negative hyporeliefs in fine-grained siliciclastic rocks. [6]
Specimens have been found in the Mistaken Point, Fermeuse, Trepassey, Shepherd Point, Rowland Head, Murphy’s Cove, and Little Catalina formations in Newfoundland, Canada, [1] [7] as well as in Bradgate Park in Charnwood Forest, Leicestershire (United Kingdom). [2] Both localities are inferred to be deep water depositional environments, [1] [2] [7] indicating that Hadrynichorde is a benthic, sessile organism. [1] Similar structures were found in the Flinders Ranges of South Australia and the White Sea areas of Russia. [3] [6]
It is theorized that Hadrynichorde could be a predecessor to extant sea whips, or Alcyonacea, which are deep marine colonial organisms. Another Ediacaran biota, Charnia, was found with Hadrynichorde in Newfoundland bedding planes. Charnia was previously associated with another marine organism known as a sea pen. Sea pens and sea whips coexist in some deep-water environments today, possibly mirroring the coexistence of Hadrynichorde and Charnia in Precambrian deep-water environments. [2]
Hadrynichorde resembles the modern cylindrical brown algae Chorda, or red algae Nemalion, but its depositional environment suggests that it is some other type of photosynthetic organism. If it was algal, it would have remained in photic zone. Hadrynichorde also bears similarity to trace fossils that are around 30 million years younger than it, which could be studied to determine the genus’ taxonomic affinity. [1] Hadrynichorde is also comparable to the ichnogenus Planolites, though affinity with this taxon is unlikely. Hadrynichorde is also similar to modern sea whips, [2] which are cnidarian organisms that exist in benthic marine environments.
Hadrynichorde is named for its appearance in Hadrynian rocks and its string-like appearance. Its species name comes from its appearance in Catalina Harbor [1]
Charnia is an extinct genus of frond-like lifeforms belonging to the Ediacaran biota with segmented, leaf-like ridges branching alternately to the right and left from a zig-zag medial suture. The genus Charnia was named for Charnwood Forest in Leicestershire, England, where the first fossilised specimen was found. Charnia is significant because it was the first Precambrian fossil to be recognized as such.
Vendobionts or Vendozoans (Vendobionta) are a proposed very high-level, extinct clade of benthic organisms that made up of the majority of the organisms that were part of the Ediacaran biota. It is a hypothetical group and at the same time, it would be the oldest of the animals that populated the Earth about 580 million years ago, in the Ediacaran period. They became extinct shortly after the so-called Cambrian explosion, with the introduction of fauna formed by more recognizable groups and more related to modern animals. It is very likely that the whole Ediacaran biota is not a monophyletic clade and not every genus placed in its subtaxa is an animal.
Charniodiscus is an Ediacaran fossil that in life was probably a stationary filter feeder that lived anchored to a sandy sea bed. The organism had a holdfast, stalk and frond. The holdfast was bulbous shaped, and the stalk was flexible. The frond was segmented and had a pointed tip. There were two growth forms: one with a short stem and a wide frond, and another with a long stalk, elevating a smaller frond about 50 centimetres (20 in) above the holdfast. While the organism superficially resembles the sea pens (cnidaria), it is probably not a crown-group animal.
Hiemalora is a fossil of the Ediacaran biota, reaching around 3 cm in diameter, which superficially resembles a sea anemone. The genus has a sack-like body with faint radiating lines originally interpreted as tentacles, but discovery of a frond-like structure seemingly attached to some Heimalora has added weight to a competing interpretation: that it represents the holdfast of a larger organism.
Rangea is a frond-like Ediacaran fossil with six-fold radial symmetry. It is the type genus of the rangeomorphs.
Bradgatia linfordensis is a bush-like Ediacaran fossil. It consists of six or more fronds radiating from a central anchor point at the base. It superficially resembles a compressed cabbage in appearance, although in reality it had a more intricate, fractal mode of organisation. When multiple fossils are found together they are regularly spaced out rather than randomly distributed. It dominates the ecosystem at 8 to 22 cm above the mud surface at the bottom the sea where it grew. It was over-towered by Charnia and Charniodiscus which grew nearby.
Thectardis avalonensis is a triangular-shaped member of the Ediacaran biota, dating from 574 to 565 million years ago. The organism took the form of an elongated cone with a central depression, and its apex was anchored to the substrate.
The Ediacaranbiota is a taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period. These were enigmatic tubular and frond-shaped, mostly sessile, organisms. Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms. The term "Ediacara biota" has received criticism from some scientists due to its alleged inconsistency, arbitrary exclusion of certain fossils, and inability to be precisely defined.
Vendiamorpha is a class of extinct animals within the Ediacaran phylum Proarticulata.
The "ivesheadiomorphs" are a group of fossilised structures known from Ediacaran localities in England and Newfoundland. They are considered to be taphomorphs, representing the poorly preserved biological remains of various contemporary taxa such as Charnia, Charniodiscus, Bradgatia, Primocandelabrum, Pectinifrons and others, that were effaced by partial decay by micro-organisms following death on the seafloor before burial by sediment.
Stromatoveris psygmoglena is a genus of basal petalonam from the Chengjiang deposits of Yunnan that was originally aligned with the fossil Charnia from the Ediacara biota. However, such an affinity is developmentally implausible and S. psygmoglena is now thought to be either a sessile basal ctenophore, or a sessile organism closely related to ctenophores. Nevertheless, a 2018 phylogenetic analysis by Jennifer Hoyal Cuthill and Jian Han indicated that Stromatoveris was a member of Animalia and closely related to ediacaran frond-like lifeforms.
Primocandelabrum is a genus of rangeomorph known from the Avalon-type Ediacaran biota. It makes up the brunt of some bedding plane assemblages. Primocandelabrum was described by Hofmann, O'Brien, and King in 2008.
The Mistaken Point Formation is a geologic formation in Newfoundland and Labrador. It is recognized as a Lagerstätte preserving fossils dating back to the Ediacaran period. It contains a stratum dated to 565 ± 3 million years ago.
The Fermeuse Formation is a fossil-bearing Ediacaran geologic formation in Newfoundland.
Until the late 1950s, the Precambrian was not believed to have hosted multicellular organisms. However, with radiometric dating techniques, it has been found that fossils initially found in the Ediacara Hills in Southern Australia date back to the late Precambrian. These fossils are body impressions of organisms shaped like disks, fronds and some with ribbon patterns that were most likely tentacles.
Parviscopa is a genus of frondose forms characterized in 2008 based on specimens from Newfoundland, Canada. Parviscopa is a member of the Ediacaran biota, and is more specifically part of the Avalon type assemblage, which is from the older part of the Ediacaran and is characterized by deep water deposits.
Frondosity is the property of an organism that normally flourishes with fronds or leaf-like structures.
Trepassia is a 579 million-year-old fossil of Ediacaran rangeomorph. It was first discovered by Guy M. Narbonne, a professor at Queen's University in Ontario, Canada and colleagues in 2009. Three years later, Martin D. Brasier added additional description to Trepassia. The generic name is taken from the French word, trépassés, which translates to "those that have departed forever" and honors the Trepassey community in Newfoundland. It was originally described as Charnia wardi; it was referred under this synonym in a 2016 paper.
Frondophyllas is an extinct, monotypic animal genus in the clade Rangeomorpha. It was found at the Mistaken Point on the Avalon Peninsula in Newfoundland, Canada in 2008 by Bamforth and Anderson. The single species is Frondophyllas grandis and as of 2021 only two specimens have been discovered. Both specimens are incomplete, but one extends to one meter long, making it one of the largest Ediacaran macrofossils. The species name: grandis, comes from its size, and the genus name: Frondophyllas means "frond with leaves". The organism has a base structure with numerous fronds attached to it. It is the only Ediacaran organism to have distinct leaflets. Evidence suggests that F. grandis may have been tethered to the seafloor and used these leaflets to "filter feed", or live off nutrients provided by a current. One of the reasons fossils of this species are so rare is because it was a soft-bodied organism. It is believed that F. grandis was preserved because it was caught beneath quickly solidifying volcanic ash. Many of the Mistaken Point fossils were preserved this way.
Hapsidophyllas is a rare Ediacaran rangeomorph fossil found at Mistaken Point, Newfoundland, Canada. It was first identified by Emily Bamforth and Guy Narbonne in 2009. Its name comes from the Greek words for “a network of leaves.” Because its characteristic flexible leaflet structure is dissimilar to other known rangeomorphs, Bamforth and Narbonne describe it as a new rangeomorph form, called hapsidophyllid. The only other known hapsidophyllid is the Ediacaran frond Frondophyllas grandis, which shares the network-like configuration of leaflets seen in Hapsidophyllas. Currently, the Hapsidophyllas flexibilis holotype resides in its type locality in the Mistaken Point Ecological Reserve, and a cast of the specimen is on display at the Royal Ontario Museum in Toronto, Canada.