{{Short description|Extinct genus of crustaceans}} {{automatic taxobox | image = | image_caption = | fossil_range= {{fossil range|Albian|Turonian|Albian-Turonian}} | taxon=Tillocheles | authority = Woods, 1957 | type_species = {{extinct}}'''''Tillocheles shannonae''''' | type_species_authority = Woods, 1957 | subdivision_ranks = Other species | subdivision = *{{extinct}}'''''T. kaoriae''''' <small>Yokoi & Karasawa, 2000</small> }}'''''Tillocheles''''' is an extinct genus of decapod crustaceans that lived during the Cretaceous period. Two species are currently placed in the genus. Fossils of the earlier type species, '''''T. shannonae''''', have been found in Queensland, while remains of the later species, '''''T. kaoriae''''', are known from Hokkaido.
==Discovery and naming== Fossils of ''Tillocheles'' were first described in 1957, when eight specimens were collected from the late Albian-aged Tambo Formation in Currane, central Queensland, Australia. Based on these specimens, Jack T. Woods erected the genus ''Tillocheles'', with ''T. shannonae'' as its type and only species. A specimen preserving part of the carapace, abdomen and appendages (F. 3252) was designated as the holotype of this species. The specific name honors Sanna Shannon, who discovered and collected fossils of decapod crustaceans at Currane.<ref name=":0">{{Cite journal |last=Woods |first=James T. |date=1957 |title=Macrurous Decapods from the Cretaceous of Queensland |url=http://www.biodiversitylibrary.org/page/48733649 |journal=Memoirs of the Queensland Museum |volume=13 |issue=3 |pages=155–175}}</ref>
In addition to the type species, a second species was assigned to ''Tillocheles'' in 2000. Named ''T. kaoriae'' (after Kaori Yokoi), it was described based on two specimens collected from the middle Yezo Group of Hokkaido, Japan. The holotype (MFM247017) was collected from Turonian-aged deposits at Obira-chō, while the paratype was found in the Cenomanian-aged Mikasa Formation at Mikasa.<ref name=":1">{{Cite journal |last1=Yokoi |first1=Takayuki |last2=Karasawa |first2=Hiroaki |date=January 2000 |title=Additions to Cretaceous decapod crustaceans from Hokkaido, Japan – Part 2. Chilenophoberidae |url=https://www.researchgate.net/publication/261711353 |journal=Bulletin of the Mizunami Fossil Museum |volume=27 |pages=191–194}}</ref>
==Description== ''Tillocheles'' was a small invertebrate, with the carapace of ''T. shannonae'' measuring around {{convert|39|mm|abbr=on|in}} long and making up about three-eighths of the total body length. Small tubercles and pits are distributed across the surface of the carapace, which is subcylindrical in shape. The rostrum is long and has two small, forward-pointing lateral spines. A deep cervical groove stretches across the top and sides of the carapace, and a pair of shallower branchiocardiac grooves run parallel to the dorsal midline. Several keels are present on the upper surface of the carapace.<ref name=":0" />
The first pair of pereiopods is elongated and large (with prodopi slightly longer than the carapace), and ending with pincers. In ''T. shannonae'' the meri of this pair of pereiopods has tubercles, whereas in ''T. kaoriae'' they have forward-pointing spines.<ref name=":1" /> Both species are heterochelate, having left and right chelipeds (pincer-bearing appendages) with different form. The left cheliped has a thicker carpus, a large compressed tooth on the pollex ("thumb" of the pincer), and a dactylus with a scalloped cutting edge. The right cheliped has an additional rows of tubercles on the prodopus, a heavy rounded tooth on the pollex and a dactylus with two rounded teeth on the cutting edge.<ref name=":0" />
The abdomen is strongly convex and large, with keels running down its length in the middle. Fine ridges surround areas with small pits on the second to sixth segments. The first segment has the smallest tergite. The telson is flattened laterally, with backward-pointing spines on the side margins and a rounded back margin.<ref name=":0" />
==Classification== In his initial description of the genus, James T. Woods assigned ''Tillocheles'' to the family Nephropidae.<ref name=":0" /> However, phylogenetic analysis done by Tshudy and Babcock (1997) found that this genus (along with several other genera then placed in Nephropidae) actually belongs in a separate family which they named Chilenophoberidae.<ref>{{Cite journal |last1=Tshudy |first1=D. |last2=Babcock |first2=L.E. |date=1997-01-01 |title=Morphology-based phylogenetic analysis of the clawed lobsters (family Nephropidae and the new family Chilenophoberidae) |journal=Journal of Crustacean Biology |language=en |volume=17 |issue=2 |pages=253–263 |doi=10.1163/193724097X00288 |bibcode=1997JCBio..17..253. |issn=0278-0372|doi-access=free }}</ref>
Further study by Karasawa ''et al.'' (2013) found that Chilenophoberidae is a paraphyletic grouping, and the family was declared a junior synonym of Stenochiridae. All chilenophoberidae genera were thus reclassified as stenochirids, including ''Tillocheles''. The following cladogram shows the placement of ''Tillocheles'' within Stenochiridae according to the study:<ref>{{Cite journal |last1=Karasawa |first1=Hiroaki |last2=Schweitzer |first2=Carrie E. |last3=Feldmann |first3=Rodney M. |date=2013-01-01 |title=Phylogeny and systematics of extant and extinct lobsters |journal=Journal of Crustacean Biology |language=en |volume=33 |issue=1 |pages=78–123 |doi=10.1163/1937240X-00002111 |bibcode=2013JCBio..33...78K |issn=0278-0372|doi-access=free }}</ref>
{{clade |label1=Stenochiridae |1={{clade |2=''Palaeophoberus'' |3='''''Tillocheles''''' |1={{clade |2=''Chilenophoberus'' |1={{clade |1=''Stenochirus'' |2=''Pseudastacus'' }} }} }} }}
==References== {{reflist}}
==External links== {{Portal|Crustaceans|Paleontology}}
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Category:Early Cretaceous crustaceans Category:Fossil taxa described in 1957 Category:Decapods Category:Late Cretaceous crustaceans Category:Albian genus first appearances Category:Cenomanian genera Category:Turonian genus extinctions Category:Cretaceous animals of Australia Category:Cretaceous arthropods of Asia Category:Crustaceans described in 1957