# Protastacus > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Protastacus > Markdown URL: https://mediated.wiki/source/Protastacus.md > Source: https://en.wikipedia.org/wiki/Protastacus > Source revision: 1354691065 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Extinct genus of crustaceans}} {{Automatic taxobox | image = Protastacus politus.jpg | image_caption = Illustration of a ''P. politus'' fossil | fossil_range= {{fossil range|Berriasian|Hauterivian|[Berriasian](/source/Berriasian)-[Hauterivian](/source/Hauterivian)}} | grandparent_authority = Albrecht, 1983 | parent_authority = Albrecht, 1983 | display_parents = 3 | taxon = Protastacus | authority = Albrecht, 1983 | type_species = {{extinct}}'''''[Astacus](/source/Astacus) politus''''' | type_species_authority = Schlüter, 1868 | subdivision = *{{extinct}}'''''P. antiquus''''' Harbort, 1905 *{{extinct}}'''''P. politus''''' Schlüter, 1868 | synonyms = {{collapsible list|bullets=true|title=''P. antiquus'' synonymy: |''Astacus antiquus'' Harbort, 1905 }} {{collapsible list|bullets=true|title=''P. politus'' synonymy: |''Astacus politus'' Schlüter, 1868 }} }} '''''Protastacus''''' is an [extinct](/source/extinct) [genus](/source/genus) of [decapod](/source/Decapoda) [crustacean](/source/crustacean)s that lived in what is now Germany during the [early Cretaceous](/source/early_Cretaceous) period. The [type species](/source/type_species) is '''''P. politus''''', and a second species, '''''P. antiquus''''', is also assigned to the genus. ''Protastacus'' grew to around {{convert|10|cm|abbr=on|in}} long and had a mostly [crayfish](/source/crayfish)-like appearance, with enlarged [pincer](/source/Pincer_(biology))-bearing appendages and a segmented [abdomen](/source/abdomen). Though formerly assigned to the [Astacidae](/source/Astacidae) or [Nephropoidea](/source/Nephropoidea), it is currently placed as the only genus in the [family](/source/Family_(taxonomy)) '''Protastacidae''', which in turn is the only family in the [superfamily](/source/Superfamily_(taxonomy)) '''Protastacoidea'''. Both known species are believed to be [brackish water](/source/brackish_water) animals, inhabiting a large upland-surrounded lake where the [Bückeberg Formation](/source/B%C3%BCckeberg_Formation) was deposited during the earliest Cretaceous. This lake was originally freshwater and connected to the [Boreal Sea](/source/Boreal_Sea), but became brackish due to [marine transgression](/source/marine_transgression). ''Protastacus'' would have lived alongside various fish, [invertebrate](/source/invertebrate)s and aquatic reptiles in this lake, while [terrestrial animal](/source/terrestrial_animal)s such as [dinosaur](/source/dinosaur)s inhabited the surrounding shores. ==Discovery and naming== left|thumb|Fossil of ''P. antiquus'' as viewed from the side Fossils of ''Protastacus'' have been described 115 years before the genus was established. In 1868, Schlüter erected the species ''[Astacus](/source/Astacus) politus'' based on remains found near [Ochtrup](/source/Ochtrup), [Germany](/source/Germany), believing it represented an extinct species of the extant [crayfish](/source/crayfish) genus ''Astacus''.{{Cite book |last1=von der Marck |first1=W. |url=https://www.zobodat.at/pdf/Palaeontographica_15_0269-0305.pdf |title=Neue fische und krebse aus der kreide von Westphalen |last2=Schlüter |first2=C. |date=1868 |publisher=Palaeontographica |location=Stuttgart |pages=269–305 |oclc=39999779}} Later in 1905, Erich Harbort studies fossilized remains in clay [ironstone](/source/ironstone) [geode](/source/geode)s found north of [Bückeberg](/source/B%C3%BCckeberg), [Germany](/source/Germany) and erects the species ''Astacus antiquus'' based on them. Harbort notes the similarity between ''A. politus'' and ''A. antiquus'', and that the two species differ in the shape of the [carapace](/source/carapace) and [uropod](/source/uropod)s. The specific name ''antiquus'' is [Latin](/source/Latin) meaning "ancient".{{Cite journal |last=Harbort |first=Erich |date=1905 |title=Die Fauna der Schaumburg-Lippe'schen Kreidemulde |url=https://www.marinespecies.org/traits./aphia.php?p=sourceget&id=440348 |format=PDF |journal=Abh. Königl. Preuss. Geol. Landesanstalt |volume=45 |pages=17–24}} Albrecht (1983) is the first to recognize that the two aforementioned species do not actually belong to ''Astacus''. He erects the genus ''Protastacus'' with ''A. politus'' as its [type species](/source/type_species) and ''A. antiquus'' as an additional species. The two are thus renamed as ''Protastacus politus'' and ''Protastacus antiquus'' respectively.{{Cite journal |last=Albrecht |first=von Henning |date=1983 |title=Die Protastacidae n. fam., fossile Vorfahren der Flußkrebse? |url=https://decapoda.nhm.org/pdfs/28239/28239.pdf |journal=Neues Jahrbuch für Geologie und Paläontologie, Monatshefte |issue=1 |pages=5–15|doi=10.1127/njgpm/1983/1983/5 }} ==Description== thumb|left|Illustration of a ''P. politus'' fossil viewed from the side A crustacean of moderate size, Harbort (1905) noted that larger specimens of ''Protastacus'' are around {{convert|10|cm|abbr=on|in}} long. The [carapace](/source/carapace) is smooth and subcylindrical in shape, with a deep cervical groove stretching across its surface. This groove first bends down the carapace sides, then bends forwards, down and forwards again to reach the front of the carapace. There are no postcervical or branchiocardiac grooves. Two keel-like projections are present lower on the sides, as well as a thornlike structure at the front of either side at the "cheek" area. Though the ends of the [antennae](/source/Antenna_(biology)) are not preserved, their bases were enlarged. thumb|Top view of a ''P. antiquus'' fossil The first three pair of [pereiopod](/source/pereiopod)s end with [pincers](/source/Pincer_(biology)), with the frontmost pair being most greatly enlarged. The first segment of the [abdomen](/source/abdomen) is small, whereas the second to sixth segments are larger and around the same size. The [exoskeletal](/source/Exoskeleton) parts of these segments are [laterally](/source/Lateral_(anatomy)) rounded and enlarged, giving the appearance that these segments are bulging at the bottom. Like the carapace, the covering of the abdomen is smooth. The [telson](/source/telson) has a subrectangular shape and the [uropod](/source/uropod)s are large, with the [exopod](/source/exopod)s being divided by a distinct suture known as the diaeresis.{{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 |issn=0278-0372|doi-access=free }} ==Classification== Although both ''Protastacus'' species were initially described as species of ''[Astacus](/source/Astacus)'', Albrecht (1983) recognized that they form a distinct genus belonging in a separate family from ''Astacus''. He named this family Protastacidae, assigning the two genera ''Protastacus'' and ''[Pseudastacus](/source/Pseudastacus)'' into it, the former being the [type genus](/source/type_genus) of the family. In 1997, Tshudy and Babcock reassigned ''Pseudastacus'' to the family [Chilenophoberidae](/source/Chilenophoberidae), leaving Protastacidae as a [monotypic family](/source/monotypic_family) with ''Protastacus'' as its only genus.{{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 |issn=0278-0372|doi-access=free }} The phylogenetic placement of Protastacidae has been a subject of controversy. Shen ''et al.'' (2001) and Schram (2001) questioned the family's placement in Astacida.{{Cite journal |last1=Shen |first1=Yanbin |last2=Schram |first2=Frederick R. |last3=Taylor |first3=Rod S. |date=2001-01-01 |title=Morphological variation in fossil crayfish of the Jehol biota, Liaoning Province, China and its texonomic discrimination |journal=Chinese Science Bulletin |language=en |volume=46 |issue=1 |pages=26–33 |doi=10.1007/BF03183202 |bibcode=2001ChSBu..46...26S |s2cid=89367581 |issn=1861-9541}}{{Cite book |last=Schram |first=Frederick R. |chapter=Phylogeny of decapods: Moving towards a consensus |date=2001 |editor-last=Paula |editor-first=José P. M. |editor2-last=Flores |editor2-first=Augusto A. V. |editor3-last=Fransen |editor3-first=Charles H. J. M. |title=Advances in Decapod Crustacean Research |chapter-url=https://link.springer.com/chapter/10.1007/978-94-017-0645-2_1 |series=Developments in Hydrobiology |language=en |location=Dordrecht |publisher=Springer Netherlands |pages=1–20 |doi=10.1007/978-94-017-0645-2_1 |isbn=978-94-017-0645-2}} In 2003, Rode and Babcock found that ''Protastacus'' belonged to the family [Astacidae](/source/Astacidae), making Protastacidae an invalid grouping.{{Cite journal |last1=Rode |first1=Alycia L. |last2=Babcock |first2=Loren E. |date=2003-01-01 |title=Phylogeny of Fossil and Extant Freshwater Crayfish and Some Closely Related Nephropid Lobsters |url=https://academic.oup.com/jcb/article-lookup/doi/10.1163/20021975-99990351 |journal=Journal of Crustacean Biology |language=en |volume=23 |issue=2 |pages=418–435 |doi=10.1163/20021975-99990351 |issn=0278-0372|url-access=subscription }} From 2009 to 2012, Protastacidae was commonly placed in the superfamily [Nephropoidea](/source/Nephropoidea) as relatives to the lobster family [Nephropidae](/source/Nephropidae).{{Cite journal |last1=De Grave |first1=Sammy |last2=Pentcheff |first2=N. Dean |last3=Ahyong |first3=Shane T. |last4=Chan |first4=Tin-Yam |last5=Crandall |first5=Keith A. |last6=Dworschak |first6=Peter C. |last7=Felder |first7=Darryl L. |last8=Feldmann |first8=Rodney M. |last9=Fransen |first9=Charles H. J. M. |last10=Goulding |first10=Laura Y. D. |last11=Lemaitre |first11=Rafael |last12=Low |first12=Martyn E. Y. |last13=Martin |first13=Joel W. |last14=Ng |first14=Peter K. L. |last15=Schweitzer |first15=Carrie E. |date=2009 |title=A Classification of Living and Fossil Genera of Decapod Crustaceans |url=http://repository.si.edu/xmlui/handle/10088/8358 |journal=The Raffles Bulletin of Zoology Supplement |language=en-US |volume=21 |pages=1–109 |hdl=10088/8358 |issn=0217-2445}}{{Cite book |last1=Schweitzer |first1=Carrie |url=https://books.google.com/books?id=iu15DwAAQBAJ&dq=info:LIwb7mJESyUJ:scholar.google.com/&pg=PA1 |title=Systematic List of Fossil Decapod Crustacean Species |last2=Feldmann |first2=Rodney |last3=Garassino |first3=Alessandro |last4=Karasawa |first4=Hiroaki |last5=Schweigert |first5=Günter |date=2010-01-07 |publisher=BRILL |isbn=978-90-474-4126-7 |language=en}}{{Cite book |last1=Schram |first1=Frederick |url=https://books.google.com/books?id=5nRDSTCPfhoC&dq=info:Ll5FBoSWyisJ:scholar.google.com/&pg=PP4 |title=Treatise on Zoology - Anatomy, Taxonomy, Biology. The Crustacea, Volume 9 Part B: Decapoda: Astacidea P.P. (Enoplometopoidea, Nephropoidea), Glypheidea, Axiidea, Gebiidea, and Anomura |last2=Klein |first2=Carel von Vaupel |date=2012-03-20 |publisher=BRILL |isbn=978-90-04-17673-7 |language=en}} Analysis by Karasawa ''et al.'' (2013) found that Protastacidae contained only the genus ''Protastacus'' and belonged in a monotypic [superfamily](/source/Superfamily_(biology)) (Protastacoidea), which is a [sister taxon](/source/sister_taxon) to the clade containing [Astacoidea](/source/Astacoidea) and [Parastacoidea](/source/Parastacoidea). The following cladogram shows the placement of ''Protastacus'' within [Astacidea](/source/Astacidea) according to the study: {{clade |1={{clade |label1=[Astacidea](/source/Astacidea) |1={{clade |1={{clade |label2={{extinct}}'''Protastacidae''' |2={{extinct}}'''''Protastacus''''' |1={{clade |1=[Parastacidae](/source/Parastacidae) |label2=[Astacoidea](/source/Astacoidea) |2={{clade |1={{clade |1={{extinct}}[Cricoidoscelosidae](/source/Cricoidoscelosidae) |2=[Cambaridae](/source/Cambaridae) }} |2=[Astacidae](/source/Astacidae) }} }} }} |2={{clade |label1=[Enoplometopoidea](/source/Enoplometopoidea) |1={{clade |1=[Enoplometopidae](/source/Enoplometopidae) |2={{extinct}}[Uncinidae](/source/Uncinidae) }} |2={{clade |1={{extinct}}[Stenochiridae](/source/Stenochiridae) |2=[Nephropidae](/source/Nephropidae) }} }} }} }} }} ==Paleoenvironment== Both of the known ''Protastacus'' species were collected from [early Cretaceous](/source/early_Cretaceous) deposits in Germany. Although Schlüter (1868) does not specify the horizon from which the fossils of ''P. politus'' were collected, Harbort (1905) states they most likely originate from the "upper Wealden", which is also where ''P. antiquus'' fossils were discovered. The "upper Wealden" here likely refers to the [Bückeberg Formation](/source/B%C3%BCckeberg_Formation), sometimes called the "German Wealden" due to its similarity to the British [Wealden Group](/source/Wealden_Group).{{Cite book |last1=Hornung |first1=Jahn J. |url=https://www.academia.edu/30830611 |title=Dinosaur Tracks 2011. An International Symposium, Obernkirchen, April 14-17, 2011. Abstract Volume and Field Guide to Excursions |last2=Böhme |first2=Annina |last3=Reich |first3=Mike |publisher=Universitätsverlag Göttingen |year=2012 |pages=62–72 |language=en |chapter=The 'German Wealden' and the Obernkirchen Sandstone – an Introduction}} ''Protastacus'' is believed to be a [brackish water](/source/brackish_water) animal, as analysis of [hydrogen](/source/hydrogen), [carbon](/source/carbon) and [sulphur](/source/sulphur) ratios as well as the presence of ''[Botryococcus](/source/Botryococcus)'' algae in the Bückeberg Formation prove the depositional environment was brackish-freshwater.{{Cite journal |last1=Froidl |first1=Felix |last2=Littke |first2=Ralf |last3=Baniasad |first3=Alireza |last4=Zheng |first4=Tianyu |last5=Röth |first5=Joschka |last6=Böcker |first6=Johannes |last7=Hartkopf-Fröder |first7=Christoph |last8=Strauss |first8=Harald |date=2021-02-01 |title=Peculiar Berriasian "Wealden" Shales of northwest Germany: Organic facies, depositional environment, thermal maturity and kinetics of petroleum generation |url=https://www.sciencedirect.com/science/article/pii/S0264817220306024 |journal=Marine and Petroleum Geology |volume=124 |article-number=104819 |doi=10.1016/j.marpetgeo.2020.104819 |bibcode=2021MarPG.12404819F |s2cid=228986602 |issn=0264-8172|url-access=subscription }} The Bückeberg Formation likely represented a large [lake](/source/lake) receiving fluvial drainage from the surrounding uplands and connected to the [Boreal Sea](/source/Boreal_Sea) to the west by narrow passage. Though originally freshwater, this lake gradually became brackish due to [marine transgression](/source/marine_transgression) caused by episodic transgressive phases and tectonic activity.{{Cite book |last=Pelzer |first=Guido |url=https://books.google.com/books?id=cmjgMQEACAAJ |title=Sedimentologie und Palynologie der Wealden-Fazies im Hannoverschen Bergland |date=1998 |publisher=Senckenbergische Naturforschende Gesellschaft |isbn=978-3-929907-49-0 |language=de}}{{Cite journal |last1=Mutterlose |first1=Jörg |last2=Bornemann |first2=André |date=December 2000 |title=Distribution and facies patterns of Lower Cretaceous sediments in northern Germany: a review |url=https://linkinghub.elsevier.com/retrieve/pii/S0195667100902325 |journal=Cretaceous Research |language=en |volume=21 |issue=6 |pages=733–759 |doi=10.1006/cres.2000.0232|bibcode=2000CrRes..21..733M |url-access=subscription }} Fossil remains of various aquatic animals have been found here which would have lived alongside ''Protastacus'', such as [mollusc](/source/mollusc)s, [crustacean](/source/crustacean)s, fish ([hybodont](/source/hybodont)s, ''[Indaginilepis](/source/Indaginilepis)'' and ''[Scheenstia](/source/Scheenstia)''), turtles (including ''[Hylaeochelys](/source/Hylaeochelys)'', ''[Pleurosternon](/source/Pleurosternon)'' and ''[Dorsetochelys](/source/Dorsetochelys)'' (=''Ballerstedtia''){{Cite journal |last=Pérez-García |first=A. |date=2014-05-01 |title=Revision of the poorly known Dorsetochelys typocardium, a relatively abundant pleurosternid turtle (Paracryptodira) in the Early Cretaceous of Europe |url=https://www.sciencedirect.com/science/article/pii/S0195667114000287 |journal=Cretaceous Research |volume=49 |pages=152–162 |doi=10.1016/j.cretres.2014.02.015 |bibcode=2014CrRes..49..152P |issn=0195-6671|url-access=subscription }}), the plesiosaur ''[Brancasaurus](/source/Brancasaurus)'', and crocodyliforms (''[Goniopholis](/source/Goniopholis)'' and ''[Pholidosaurus](/source/Pholidosaurus)''). [Terrestrial animal](/source/Terrestrial_animal)s that would have lived on the lake shores are also represented, including body fossils of the dinosaurs ''[Stenopelix](/source/Stenopelix)'' and ''[Hylaeosaurus](/source/Hylaeosaurus)'', as well as footprints of various dinosaurs and [pterosaur](/source/pterosaur)s.{{Cite book |last1=Böhme |first1=Annina |url=https://www.researchgate.net/publication/235944267 |title=Dinosaur Tracks 2011. An International Symposium, Obernkirchen, April 14-17, 2011. Abstract Volume and Field Guide to Excursions |last2=Reich |first2=Mike |last3=Hornung |first3=Jahn J. |last4=Karl |first4=Hans-Volker |publisher=Universitätsverlag Göttingen |year=2012 |pages=62–72 |language=en |chapter=Northern 'German Wealden' – the collection of the Göttingen University}}{{Cite journal |last1=Sachs |first1=Sven |last2=Hornung |first2=Jahn J. |date=2013-04-03 |editor-last=Evans |editor-first=David C. |title=Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany |journal=PLOS ONE |language=en |volume=8 |issue=4 |article-number=e60571 |doi=10.1371/journal.pone.0060571 |issn=1932-6203 |pmc=3616133 |pmid=23560099 |bibcode=2013PLoSO...860571S |doi-access=free }} ==References== {{Reflist}} ==External links== {{Portal|Crustaceans|Paleontology}} *{{commons category-inline|Protastacus|''Protastacus''}} {{Taxonbar|from=Q124005585|from2=Q21228549|from3=Q33189315}} Category:Early Cretaceous crustaceans Category:Fossil taxa described in 1983 Category:Decapods Category:Early Cretaceous arthropods of Europe Category:Berriasian genus first appearances Category:Hauterivian genus extinctions Category:Valanginian genera Category:Crustaceans described in 1983 --- Adapted from the Wikipedia article [Protastacus](https://en.wikipedia.org/wiki/Protastacus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Protastacus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.