Lenisambulatrix

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Lenisambulatrix
Temporal range: Cambrian Stage 3
Three-dimensional reconstruction of Lenisambulatrix humboldti.jpg
Three-dimensional reconstruction of Lenisambulatrix humboldti
20210928 Lenisambulatrix humboldti diagrammatic reconstruction.png
Diagrammatic reconstruction of Lenisambulatrix humboldti
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
(unranked): Panarthropoda
Phylum: "Lobopodia"
Genus: Lenisambulatrix
Species:
L. humboldti
Binomial name
Lenisambulatrix humboldti
Ou & Mayer, 2018

Lenisambulatrix (Humboldt lobopodian) 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. [1] 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. [2]

Contents

Discovery

Lenisambulatrix humboldti fossils Lenisambulatrix humboldti fossil.jpg
Lenisambulatrix humboldti fossils

The fossil of Lenisambulatrix humboldti was discovered by Qiang Ou (China University of Geosciences, Beijing, China) and Georg Mayer (University of Kassel, Kassel, Germany). It was found in the Heilinpu Formation of the Huaguoshan section at Sanjiezi village, Erjie town, Yunnan, South China. [1] The location is dated to Cambrian Series 2, Stage 3 (about 520 million years old). [3] [4] The excavation also yielded a fossil of Diania cactiformis, already described by Ou's team in 2011. [5] The specimen was compressed partly with the fossil of a brachiopod Diandongia pista, which was described from the similar Maotianshan shale in 2003. [6] The discovery was reported in the September issue of the Scientific Reports . [7]

The generic name is derived from Latin words, lenis, meaning soft or smooth, or gentle, attributing to the smooth unarmoured body; ambulatrix, meaning walker. The specific name is in honour of the German zoologist Friedrich Wilhelm Heinrich Alexander von Humboldt, after whose name was established the Alexander von Humboldt Foundation, which funded the research. [2]

Description

Lenisambulatrix is seen as dark, carbonaceous and aluminosilicate films in a worn out mudstone. The original soft tissues and cuticle are represented by deposits of dark red to brown iron(III) oxide fine grains as a result of weathering of microscopic diagenetic pyrite. [2] This fossilisation process is similar to those of other specimens in the Chengjian region. [8] The fossil is oblique-ventrally compressed and the remaining parts are nicely preserved showing details of the body structure. This good preservation is characteristic of Chengjian biota and indicates death due to a catastrophic event. [9]

The worm is a soft-bodied lobopodian without any hard part (sclerotized) surface, thus, appears naked [1] in contrast to most lobopodians which bears spines as body armours. [10] [11] It is not preserved in a completely stretched form and many parts are missing. The measurable length of the body is 2.9 cm; with a width varying from 2 to 3.6 mm. The trunk consists of at least eight segments (somites), each of which bears a pair of thick and long legs. The fossil contains only the anterior part and the posterior region remains unknown. [2] The head part is slightly extended and does not show any specific part. It is believed to be closely related to Diania, but with unique differences. The main distinction is numerous sclerotized spines that adorn Diana are completely absent in Lenisambulatrix. [1] Diana's head is also much more rounded and shorter. The general outline of Lenisambulatrix's head more similar to other lobopodians such as Microdictyon sinicum , Paucipodia inermis , and Hallucigenia sparsa. [10] [12] [13] However, the relatively thick and elongated legs measuring 11.6 to 18 mm long are unique to both Diania and Lenisambulatrix. [7] Their legs also lack claws that are the common features in other lobopods. [11] [14] The legs indicate that they were adapted to walking or crawling on the bottom of waters. [7] The simple body structure suggests that Lenisambulatrix is one of the earliest panarthropod animal. [2]

Related Research Articles

<span class="mw-page-title-main">Lobopodia</span> Group of extinct worm-like animals with legs

The lobopodians, members of the informal group Lobopodia, or the formally erected phylum Lobopoda Cavalier-Smith (1998), are panarthropods with stubby legs called lobopods, a term which may also be used as a common name of this group as well. While the definition of lobopodians may differ between literatures, it usually refers to a group of soft-bodied, worm-like fossil panarthropods such as Aysheaia and Hallucigenia.

<i>Hallucigenia</i> Genus of Cambrian animals

Hallucigenia is a genus of Cambrian animal resembling worms, known from articulated fossils in Burgess Shale-type deposits in Canada and China, and from isolated spines around the world. The generic name reflects the type species' unusual appearance and eccentric history of study; when it was erected as a genus, H. sparsa was reconstructed as an enigmatic animal upside down and back to front. Hallucigenia was later recognized as a lobopodian, a grade of Paleozoic panarthropods from which the velvet worms, water bears, and arthropods arose.

<span class="mw-page-title-main">Maotianshan Shales</span> Series of Early Cambrian deposits in the Chiungchussu Formation

The Maotianshan Shales 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.

<i>Xenusion</i> Extinct genus of panarthropods

Xenusion auerswaldae is an early lobopodian known from two specimens found in glacial erratics on the Baltic coast of Germany. They probably originated in the Kalmarsund Sandstone of Southern Sweden, which was deposited in the Lower Cambrian. It is the oldest currently known lobopodian with soft body fossils.

<span class="mw-page-title-main">Dinocaridida</span> Extinct class of basal arthropods

Dinocaridida is a proposed fossil taxon of basal arthropods that flourished in the Cambrian period with occasional Ordovician and Devonian records. Characterized by a pair of frontal appendages and series of body flaps, the name of Dinocaridids comes from Greek, "deinos" and "caris", referring to the suggested role of some of these members as the largest marine predators of their time. Dinocaridids are occasionally referred to as the 'AOPK group' by some literatures, as the group compose of Radiodonta, Opabiniidae, Pambdelurion and Kerygmachela. It is most likely paraphyletic, with Kerygmachela and Pambdelurion more basal than the clade compose of Opabiniidae, Radiodonta and other arthropods.

<i>Vetulicola</i> Cambrian age animal genus

Vetulicola is a genus of extinct marine animals 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.

<i>Pambdelurion</i> Extinct genus of Arthropod

Pambdelurion is an extinct genus of panarthropod from the Cambrian aged Sirius Passet site in northern Greenland. Like the morphologically similar Kerygmachela from the same locality, Pambdelurion is thought to be closely related to arthropods, combining characteristics of "lobopodians" with those of primitive arthropods.

<i>Miraluolishania</i> Extinct genus of lobopodians

Miraluolishania is an extinct lobopodian known from Chengjiang County in China. It is remarkable for the possession of lensed pit-eyes. The only species, Miraluolishania haikouensis, was described from the Maotianshan Shales at Haikou by Jianni Liu and Degan Shu in 2004. In 2009, a team of palaeontologists at the Yunnan University, led by Xiaoya Ma reported the discovery of 42 other specimens from Haikou. With the help of Swiss palaeontologist Jan Bergström, Ma and Hou came to the conclusion that all the specimens were the same species as Luolishania; another lobopod discovered from the Chengjian in 1989. Chengjian is 40 kms from Haikou and the fossil fauna are different. A reassessment by Liu and Shu's team at the Northwest University in 2008 established that Luolishania and Miraluolishania are distinct animals.

<i>Vetulicola cuneata</i>

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.

<i>Diania</i> Extinct genus of Cambrian animals

Diania is an extinct genus of lobopodian panarthropod found in the Lower Cambrian Maotianshan shale of China, represented by a single species - D. cactiformis. Known during its investigation by the nickname "walking cactus", this organism belongs to a group known as the armoured lobopodians, and has a simple worm-like body with robust, spiny legs. Initially, the legs were thought to have a jointed exoskeleton and Diania was suggested to be evolutionarily close to early arthropods, but many later studies have rejected this interpretation.

<span class="mw-page-title-main">Luolishaniidae</span> Extinct family of worm-like animals

The Luolishaniidae or Luolishaniida are a group of Cambrian and Ordovician lobopodians with anterior 5 or 6 pairs of setiferous lobopods. Most luolishaniids also have posterior lobopods each with a hooked claws, and thorn-shaped sclerites arranged as three or more per trunk segment. The type genus is based on Luolishania longicruris Hou and Chen, 1989, from the Chengjiang Lagerstatte, South China. They are presumed to have been benthic suspension or filter feeders.

<i>Antennacanthopodia</i> Extinct genus of lobopodians

Antennacanthopodia is a rare unarmoured lobopodian from the Chengjiang biota, with prickly legs, a pair of 'antennae', and an onychophoran-like body outline. It also has a pair of frontal antennae, potential ocellus-like lateral visual organs, second antennae possibly homologous to the slime papillae of modern Onychophorans, a straight, voluminous midgut, diminutive spines arrayed on the leg and the trunk, well-developed leg musculature, highly sclerotized terminal leg pads, and presumptively a pair of posteriormost appendicules.

<i>Vetulicola rectangulata</i>

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.

<i>Onychodictyon</i> Extinct genus of worms

Onychodictyon is a genus of extinct lobopodian known from the Lower Cambrian Chengjiang Maotianshan Shales in the Yunnan Province in China. It was characterized by a stout body covered by fleshy papillae and pairs of sclerotized plates with spines, representing part of the diverse "armoured lobopodians" alongside similar forms such as Microdictyon and Hallucigenia.

<i>Acinocricus</i> Extinct genus of worms

Acinocricus is a genus of extinct worm belonging to the group Lobopodia and known from the middle Cambrian Spence Shale of Utah, United States. As a monotypic genus, it has one species Acinocricus stichus. The only lobopodian discovered from the Spence Shale, it was described by Simon Conway Morris and Richard A. Robison in 1988. Owing to the original fragmentary fossils discovered since 1982, it was initially classified as an alga, but later realised to be an animal belonging to Cambrian fauna.

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.

<i>Thanahita</i> Extinct genus of Lobopodian

Thanahita is a genus of extinct lobopodian and known from the middle Silurian Herefordshire Lagerstätte at the England–Wales border in UK. It is monotypic and contains one species, Thanahita distos. Discovered in 2018, it is estimated to have lived around 430 million years ago and is the only known extinct lobopodian in Europe, and the first Silurian lobopodian known worldwide.

<span class="mw-page-title-main">Hallucigeniidae</span>

Hallucigeniidae is a family of extinct worms belonging to the group Lobopodia that originated during the Cambrian explosion. It is based on the species Hallucigenia sparsa, the fossil of which was discovered by Charles Doolittle Walcott in 1911 from the Burgess Shale of British Columbia. The name Hallucigenia was created by Simon Conway Morris in 1977, from which the family was erected after discoveries of other hallucigeniid worms from other parts of the world. Classification of these lobopods and their retatives are still controversial, and the family consists of at least four genera.

<i>Laminacaris</i> Genus of extinct arthropods

Laminacaris is a genus of extinct stem-group arthropods (Radiodonta) that lived during the Cambrian period. It is monotypic with a single species Laminacaris chimera, the fossil of which was described from the Chengjian biota of China in 2018. Around the same time, two specimens that were similar or of the same species were discovered at the Kinzers Formation in Pennsylvania, USA. The first specimens from China were three frontal appendages, without the other body parts.

References

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