Cretoperipatus
{{Short description|Extinct species of peripatid velvet worm found in amber}}
{{Speciesbox
| fossil_range = Cenomanian-Turonian {{fossilrange|100|90}}
| image = Cretoperipatus.jpg
| genus = Cretoperipatus
| parent_authority = Engel & Grimaldi, 2002
| species = burmiticus
| authority = Engel & Grimaldi, 2002
}}
Cretoperipatus burmiticus is an extinct species of peripatid velvet worm known from multiple specimens in Burmese amber. It lived in Myanmar's Kachin State during the Cenomanian Age of the Late Cretaceous. Some fossils were exceptionally preserved, allowing detailed analysis of its fine anatomy. Cretoperipatus had a pair of antennae, two simple eyes, clawed legs, and a pair of slime papillae, showing it was it was a crown-group onychophoran. Based on details of its fine anatomy, Cretoperipatus was placed in the family Peripatidae, likely grouping with basal Asian species like Eoperipatus and Typhloperipatus.
Discovery and naming
Both the holotype (AMNH Bu218) and various topotypes (BU-001467, BU-001468, ZZZ0066) were found in Burmese amber near Tanai in Myanmar's Kachin State.{{cite journal |last1=Grimaldi |first1=David A. |last2=Engel |first2=Michael S. |last3=Nascimbene |first3=Paul C. |date=March 2002 |title=Fossiliferous Cretaceous Amber from Myanmar (Burma): Its Rediscovery, Biotic Diversity, and Paleontological Significance |url=https://www.biodiversitylibrary.org/bibliography/178519 |journal=American Museum Novitates |issue=3361 |pages=1–71 |doi=10.1206/0003-0082(2002)361<0001:FCAFMB>2.0.CO;2 |s2cid=53645124 |hdl=2246/2914}}{{cite journal |last1=Oliveira |first1=I. S. |last2=Bai |first2=M |last3=Jahn |first3=H |last4=Gross |first4=V |last5=Martin |first5=C |last6=Hammel |first6=J. U. |last7=Zhang |first7=W |last8=Mayer |first8=G |date=2016 |title=Earliest Onychophoran in Amber Reveals Gondwanan Migration Patterns |journal=Current Biology |volume=26 |issue=19 |pages=2594–2601 |bibcode=2016CBio...26.2594O |doi=10.1016/j.cub.2016.07.023 |pmid=27693140 |doi-access=free}} Additional unsubscribed specimens were found in the same location, showing this animal was fairly abundant. All fossils date to around 100 million years ago, meaning the animal lived at the beginning of the Late Cretaceous during the Cenomanian Age.
The genus name "Cretoperipatus" is derived from "creto-", since it lived in the Cretaceous and "Peripatus", the type genus of the family Peripatidae. The species name "burmiticus" references the fossil being encased in Burmese amber.
Description
Due to being encased in amber, many Cretoperipatus specimens preserve minute details that would otherwise disappear in the typical fossilization process. One specimen (BU-001468) was even preserved in three dimensions, allowing researchers to create an intricate 3D render of its anatomy.
= Dermal Papillae =
Cretoperipatus
= Head =
Cretoperipatus had a single pair of antennae with simple eyes called ocelli at their base. The top of the antenna possessed rings of specialized primary papillae known as type 1 sensilla. These are distinguished from regular primary papillae by their prominent apical piece and bristle with a textured base.{{Cite journal |last1=Oliveira |first1=Ivo de Sena |last2=Franke |first2=Franziska Anni |last3=Hering |first3=Lars |last4=Schaffer |first4=Stefan |last5=Rowell |first5=David M. |last6=Weck-Heimann |first6=Andreas |last7=Monge-Nájera |first7=Julián |last8=Morera-Brenes |first8=Bernal |last9=Mayer |first9=Georg |date=2012-12-17 |title=Unexplored Character Diversity in Onychophora (Velvet Worms): A Comparative Study of Three Peripatid Species |journal=PLOS ONE |language=en |volume=7 |issue=12 |pages=e51220 |doi=10.1371/journal.pone.0051220 |doi-access=free |issn=1932-6203 |pmc=3524137 |pmid=23284667|bibcode=2012PLoSO...751220O }} The undersides of the antennae possessed an array of spindle-shaped sensilla. These papillae are similar to type 1 sensilla, but have a large, spindly-shaped basal piece. In addition to papillae, the animal possessed a pair of frontal organs at the base of the antennae and beneath the eyes.
Cretoperipatus had a ventral (bottom-facing) mouth with two internal jaws. In the original description, the animal's genital pad was mistaken for the mouth. This was due to the holotype's poor preservation and the two structures looking similar. When looking at the structure of its internal jaws, these possessed a diastema and diastemal membrane. Cretoperipatus also possessed a pair of slime papillae. These were somewhat hard to distinguish, even when using x-ray microscopy.
= Trunk =
Cretoperipatus had around twelve annuli or rings of dermal papillae on each segment of its trunk. The annuli were composed of both primary and accessory papillae and did not fuse laterally. Cretoperipatus had a visible dorsal midline running along the middle of its back. On its underside, the trunk preserved traces of the ventral and preventral organs. At the very end of this, Cretoperipatus had a genital pad between its penultimate (second to last) pair of legs.
= Lobopods =
Cretoperipatus had a pair of legs known as lobopods on each segment of its trunk. Like in other velvet worms, the lobopods had a papillae-covered base, spinose pads or cushions, and a clawed foot. The animal had no coxal organs on any legs and lacked crural papillae on the front-most pairs. However, all legs have a nephridal opening at their base.
Cretoperipatus was originally interpreted as having only three spiny pads per lobopod, yet better specimens show most of them have four. The original describers probably mistook the holotype's back with its front as this specimen was poorly preserved, and a velvet worm's endmost legs have fewer cushions. On a typical leg of Cretoperipatus, the distal (furthest away from the trunk) and proximal (closest to the trunk) cushions are thinner than the two between. The third cushion (2nd closest to the body) was also split in two by a nephridial tubercle, an organ used to dispel waste.
Cretoperipatus{{'}}s foot had five basal papillae, with the bottom-most two being weakly developed. At the end of the foot were two distal papillae. These were located on either side of a pair of claws. Many of these claws were detached and found floating in the amber matrix. This makes sense, as in modern velvet worms, the claws are connected by only a fragile membrane of tissue.
Classification
|1={{clade
|1=Eoperipatus
|2={{clade
|2=†Cretoperipatus
}}
}}
|2={{clade
|2=Neopatida
}}
}}|label1=Peripatidae}}
Cretoperipatus was assigned to Peripatidae based on the following characteristics: the papillae on its back could be divided into two parts (basal and apical), its genital pad was between the penultimate legs, it possessed spindle-shaped sensilla on its antennae, and it had a diastema on its jaw blade.
Cretoperipatus was grouped with various South Asian species due to having two distal papillae (other peripatids have three or more). It lacked ventral fields of modified scales present in Eoperipatus totoro, but these are also lacking in other species of Eoperipatus. Unlike Eoperipatus but similar to Typhloperipatus, the foot's nephridial tubercle was on the third spinous pad rather than higher up. However, unlike Typhloperipatus, Cretoperipatus still had eyes.
Implications
= Zoogeography =
Early on, it was hypothesized that onychophorans arrived in Asia due to northwards drift of India, which, at the time, was an independent continent. This was known as the "Out of India" hypothesis and explained how velvet worms colonized South and Southeast Asia. Cretoperipatus refutes this, as it had clear affinities with Asian velvet worms and was present before the Asia-India collision during the Late Oligocene. Some time after this, peripatids began colonizing Northeast India, probably from Myanmar. Combined with the presence of other Northern Hemisphere onychophorans (Antennipatus, Helenodora, and tentatively Succinipatopsis), velvet worms occurred in Laurasia (the precursor of North America and Eurasia) far longer than originally thought.{{Cite journal |last1=Murienne |first1=Jerome |last2=Daniels |first2=Savel R. |last3=Buckley |first3=Thomas R. |last4=Mayer |first4=Georg |last5=Giribet |first5=Gonzalo |date=2014-01-22 |title=A living fossil tale of Pangaean biogeography |journal=Proceedings of the Royal Society B: Biological Sciences |volume=281 |issue=1775 |pages=20132648 |doi=10.1098/rspb.2013.2648 |pmc=3866409 |pmid=24285200}}
References
= Citations =
{{Reflist}}
External links
- {{Wikispecies-inline|Cretoperipatus|Cretoperipatus}}
{{Onychophora}}
{{Taxonbar|from1=Q15149849|from2=Q144451}}
Category:Prehistoric onychophorans
Category:Late Cretaceous invertebrates
Category:Cretaceous invertebrates of Asia
Category:Monotypic onychophoran genera
Category:Onychophorans of southeast Asia
Category:Fossil taxa described in 2002
Category:Taxa named by Michael S. Engel