Tylopterella

Edit links
This is a good article. Click here for more information.
Source: Wikipedia, the free encyclopedia.

Tylopterella
Temporal range:
Ma
↓
Top view of the holotype specimen of T. boylei recovered at Elora, in Canada. Carapace ornamentation enlarged.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Order: †Eurypterida
Superfamily: †Onychopterelloidea
Family: †Onychopterellidae
Genus: †Tylopterella
Størmer, 1951
Type species
†Tylopterella boylei
Whiteaves, 1884

Tylopterella is a

epoch) in Elora, Canada. The name of the genus is composed by the Ancient Greek words τύλη (túlē), meaning "knot", and πτερόν (pteron), meaning "wing". The species name boylei honors David Boyle
, who discovered the specimen of Tylopterella.

It is a poorly-known genus whose

laterally placed, a preabdomen and postabdomen (the two halves of the abdomen) with six segments each and a short spike-like telson (which was the posteriormost division of the body). It reached a total length of 7.5 centimetres (2.9 inches). These characteristics place Tylopterella in the family Onychopterellidae together with Onychopterella and Alkenopterus
.

Tylopterella is notable for its thick ornamentation and general body surface. Its paired tubercles or knobs in the top of its second to fifth segments differentiates it from many other eurypterids. This thickness that its body possessed is due to the highly saline conditions to which Tylopterella had to adapt in the Guelph Formation; other organisms with reinforced shells have also been found in the same place.

Description

Size comparison of T. boylei

Like the other

onychopterellids, Tylopterella was a small eurypterid. The total size of the only known specimen is estimated at only 7.5 centimetres (2.9 inches).[1]

Tylopterella is a little-known

organs) were located. The surface of the carapace was granulate (with granules) and had an ornamentation which consisted of minute rounded tubercles, some isolated and others confluent in sets of two or three. It was strengthened by prominent calcareous (with calcium) deposits.[1]

As in the rest of eurypterids, the

tergites (dorsal half of the segment) carried in its median line a pair of single large, solid, prominent and elongated tubercles or knobs.[2] They were reniform at the base and somewhat bilobed (with two lobes) at the top. The telson (the posteriormost division of the body) was like a gradually narrowing, slightly curved and pointed spine. It reached a length of 1.5 cm (0.6 in).[1] Fragments of the fourth appendage (limb) and the paddle of the swimming leg (sixth and last pair of appendages) are also preserved.[2]

History of research

Elora is located in Ontario
Elora
Elora
class=notpageimage|
Location of Elora in Ontario, where the only known specimen of T. boylei has been recovered

Tylopterella is known by one single specimen (making it the

paleontologist. He erected a new species of the genus Eurypterus for it, E. boylei, whose specific name honors its discoverer.[1]

In 1912, the American paleontologists

brackish or fresh water while Tylopterus lived in very saline water). The name Tylopterus is composed by the Ancient Greek words τύλη (túlē, "knot"), and πτερόν (pteron, "wing"), therefore translated as "knot wing".[2]

In 1951, the Norwegian paleontologist and

scientific papers as a separate genus from Eurypterus for no apparent reason.[4][5] It was not until 1958 when its status as a separate genus was reaffirmed by the American paleontologist Erik Norman Kjellesvig-Waering, who claimed that Tylopterella differed from any other eurypterid genus by its peculiar ornamentation.[6]

In 1962, a species of

monotypic again.[7]

Classification

Restoration of Onychopterella, a closely related onychopterellid genus

Tylopterella is classified as part of the

superfamily Onychopterelloidea. It includes a single species, T. boylei, from the Silurian of the Guelph Formation of Elora, Canada.[1][8]

Originally described as a species of Eurypterus,[1] Tylopterella was recognized as a different subgenus in 1912.[2] In 1951, the British professor Scott Simpson compared the tubercles of Drepanopterus abonensis with those of Tylopterella, recognizing the validity of the genus reluctantly on the basis that the only known specimen of Tylopterella could be referred to both Drepanopterus and Stylonurus.[5] Kjellesvig-Waering identified Tylopterella as a genus of its own, but due to similarities with Erieopterus microphthalmus and E. eriensis, he suggested that T. boylei could have descended directly from Erieopterus.[6] Tylopterella was classified as part of the family Eurypteridae until 1989, when the American paleontologist Victor P. Tollerton classified it as incertae sedis (a taxon with unclear relationships) due to the scarce material and lack of obvious features of any family.[9]

However, in 2011, the British geologist and

podomere, that is, leg segment of the sixth appendage), the shape of the carapace with lateral eyes and a lanceolate or styliform telson. Lamsdell rejected any alliance between Drepanopterus and Tylopterella.[3] Alkenopterus was assigned to Onychopterellidae three years later because of the detection of a movable spine in the swimming leg, rather than a simple projection (a protruding body part) as previously thought.[10]

The

derived groups.[3]

 

Paleoecology

The only known fossil of Tylopterella was recovered from

mollusks with thickened shells as well as the matrix of the fossil of Tylopterella, a porous coarse-grained dolomite, indicates the same.[2] Therefore, Tylopterella represents the only eurypterid adapted to hypersalinity.[12]

T. boylei is the only eurypterid found in its fossil site. It is associated with

subtidal (that is, the sunlight reaches the bottom of the ocean) sea, and its lithology (the physical characteristics of the rocks) consists mainly of dolomite with presence of petroleum.[11]

See also

References

  1. ^ a b c d e f g h Whiteaves, Joseph F. (1884). "On some new, imperfectly characterized or previously unrecorded species of fossils from the Guelph Formations of Ontario". Palaeozoic Fossils of Canada. 3 (1): 1–43.
  2. ^
    ISBN 978-1125460221
    .
  3. ^
    S2CID 251107327
    .
  4. S2CID 129426407. Archived
    from the original on 2018-12-30. Retrieved 2018-12-29.
  5. ^
    doi:10.1080/00222935108654216
    .
  6. ^
    JSTOR 1300776
    .
  7. S2CID 84434367
    .
  8. Natural History Museum Bern
    .
  9. S2CID 46953627. Archived
    from the original on 2019-03-24. Retrieved 2018-12-29.
  10. S2CID 132432538
    .
  11. ^ a b "Eurypterid-associated biota of the dolomite of the Lockport Fmn. at Elora, Ont. (Silurian of Canada)". The Paleobiology Database.
  12. doi:10.1016/j.palaeo.2015.12.011
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=Tylopterella&oldid=1184154244"