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Genus of horseshoe crab relatives
Willwerathia Temporal range:
Lower Devonian
Reconstruction of Willwerathia laticeps
Scientific classification
Kingdom:
Phylum:
Subphylum:
Order:
Genus:
†Willwerathia Størmer, 1969
Species
Willwerathia laticeps (Størmer, 1936a)
Willwerathia is a
genus of Devonian
arthropod . It is sometimes classified as
synziphosurine ,
[1]
[2] a
paraphyletic group of
horseshoe crab -like
fossil
chelicerate arthropods,
[2] while some studies compare its morphology to an
artiopod .
[3]
[4] Willwerathia known only by one
species , Willwerathia laticeps , discovered in
deposits of the
Devonian
period from the
Klerf Formation , in the
Rhenish Slate Mountains of
Germany .
[1]
[5]
Morphology
Size comparison of Willwerathia (A) and other
synziphosurines .
As a
synziphosurine , Willwerathia is unusually large and so far the largest known synziphosurine, with largest
carapace measured about 90mm in width.
[1]
Prosoma of Willwerathia covered by a vaulted carapace with pointed genal spines, recurved (M-shaped) ophthalmic ridges and pairs of dorsal nodes.
[1]
Tergites of the
opisthosoma are either incomplete or disarticulated in available
fossil materials, making it difficult to reveal the original number of opisthosomal segments.
[1] The opisthosoma of Willwerathia most likely compose of 10 segments, each expressed by a tergite that bore a median dorsal spine and a pair of tergopleurae (lateral extensions).
[1] The opisthosoma subdivided into a wider, most likely 7-segmented preabdomen and a narrower, 3-segmented postabdomen.
[1] tergite of the first opisthosomal segment is reduced in length while the remaining segments possess well-developed tergites with lateral nodes and posteriorly curved tergopleurae. The final segment terminated with a short, teardrop-shaped
telson .
[1]
Paleoecology
Willwerathia was most likely a bottom-dwelling
predator .
[1] The marked articulation surfaces on each of the preabdominal segments suggest that Willwerathia capable to enroll itself in a way similar to
Legrandella .
[1] The environment in which Wilwerathia lived in was likely an
estuarine to
deltaic one, and other animals like the largest
eurypterid ,
Jaekelopterus , are known from the same formation.
[6]
Classification
Falcatamacaris
Willwerathia was originally thought to be an
eurypterid (sea scorpion), with additional fossils described in 1998 reveal its
synziphosurine affinities.
[1] In the redescription done by Anderson et al. 1998, Willwerathia had been grouped under the synziphosurine
family
Weinberginidae alongside
Weinbergina and
Legrandella ,
[1] a classification which is not supported by
phylogenetic analysis.
[2] Willwerathia was regarded as part of the
monophyletic
Xiphosura sensu stricto (true horseshoe crab) by Lamsdell 2013,
[2]
[7] but further phylogenetic analysis repeatedly resolving it within a
clade compose of
Bunodids ,
Pseudoniscids and
Dekatriatan (
chasmataspidids , eurypterids and
arachnids ).
[8]
[9]
[10]
[11] Morphology of
Silurian -Devonian arthropd
Maldybulakia is sometimes compared to that of Willwerathia .
[4]
[12] However, in 2020, Lamsdell found that Willwerathia bears a strong resemblance to the
Cambrian
artiopod
Falcatamacaris , while it does not bear resemblance to other chelicerates.
[3]
References
^
a
b
c
d
e
f
g
h
i
j
k
l Anderson, Lyall I.; Poschmann, Markus; Brauckmann, Carsten (1998).
"On the Emsian (Lower Devonian) arthropods of the Rhenish Slate Mountains: 2. The synziphosurine Willwerathia " . Paläontologische Zeitschrift . 72 (3–4): 325–336.
doi :
10.1007/BF02988363 .
ISSN
0031-0220 .
S2CID
128464147 .
^
a
b
c
d Lamsdell, James C. (2013-01-01).
"Revised systematics of Palaeozoic 'horseshoe crabs' and the myth of monophyletic Xiphosura" . Zoological Journal of the Linnean Society . 167 (1): 1–27.
doi :
10.1111/j.1096-3642.2012.00874.x .
ISSN
0024-4082 .
^
a
b Lamsdell, James C. (2020-09-01).
"A chasmataspidid affinity for the putative xiphosuran Kiaeria Størmer, 1934" . PalZ . 94 (3): 449–453.
doi :
10.1007/s12542-019-00493-8 .
ISSN
1867-6812 .
^
a
b Zong, Ruiwen; Edgecombe, Gregory D.; Liu, Bingcai; Wang, Yi; Yin, Jiayi; Ma, Juan; Xu, Honghe (2023). Cherns, Lesley (ed.).
"Silurian freshwater arthropod from northwest China" . Papers in Palaeontology . 9 (2): e1488.
doi :
10.1002/spp2.1488 .
ISSN
2056-2799 .
^ Dunlop, J. A.; Penney, D.; Jekel, D. (2020).
"A summary list of fossil spiders and their relatives" (PDF) . World Spider Catalog .
Natural History Museum Bern . pp. 1–296.
^ Poschmann, Markus; Tetlie, O. Erik (2006-12-01).
"On the Emsian (Lower Devonian) arthropods of the Rhenish Slate Mountains: 5. Rare and poorly known eurypterids from Willwerath, Germany" . Paläontologische Zeitschrift . 80 (4): 325–343.
doi :
10.1007/BF02990208 .
^ Bicknell, Russell D. C.; Pates, Stephen (2020).
"Pictorial Atlas of Fossil and Extant Horseshoe Crabs, With Focus on Xiphosurida" . Frontiers in Earth Science . 8 : 98.
Bibcode :
2020FrEaS...8...98B .
doi :
10.3389/feart.2020.00098 .
ISSN
2296-6463 .
S2CID
220405124 .
^ Selden, Paul A.; Lamsdell, James C.; Qi, Liu (2015).
"An unusual euchelicerate linking horseshoe crabs and eurypterids, from the Lower Devonian (Lochkovian) of Yunnan, China" . Zoologica Scripta . 44 (6): 645–652.
doi :
10.1111/zsc.12124 .
ISSN
0300-3256 .
S2CID
55264483 .
^ Lamsdell, James C.; Briggs, Derek E. G.; Liu, Huaibao P.; Witzke, Brian J.; McKay, Robert M. (2015).
"A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids" . The Science of Nature . 102 (9–10): 63.
Bibcode :
2015SciNa.102...63L .
doi :
10.1007/s00114-015-1312-5 .
ISSN
0028-1042 .
PMID
26391849 .
S2CID
8153035 .
^ Lamsdell, James C. (2016).
"Horseshoe crab phylogeny and independent colonizations of fresh water: ecological invasion as a driver for morphological innovation" . Palaeontology . 59 (2): 181–194.
doi :
10.1111/pala.12220 .
ISSN
1475-4983 .
S2CID
85553811 .
^ Bicknell, Russell D. C.; Lustri, Lorenzo; Brougham, Tom (2019-12-01).
"Revision of "Bellinurus" carteri (Chelicerata: Xiphosura) from the Late Devonian of Pennsylvania, USA" . Comptes Rendus Palevol . 18 (8): 967–976.
doi :
10.1016/j.crpv.2019.08.002 .
ISSN
1631-0683 .
^ Lamsdell, James C. (2013-01-01).
"Revised systematics of Palaeozoic 'horseshoe crabs' and the myth of monophyletic Xiphosura" . Zoological Journal of the Linnean Society . 167 (1): 1–27.
doi :
10.1111/j.1096-3642.2012.00874.x .
ISSN
0024-4082 .
S2CID
82434358 .