(ieol. Jb. Hessen 127:71-81, 10 Abb., I Tab.; Wiesbaden HID!)

Alessandro Garassino1, Hans Hagdorn- & Manfred Schulz !

A decapod crustacean assemblage from the Middle Triassic Upper Muschelkalk of Grofienliider (Hessen, Germany)

K u r / f a s s u n g

Ini Oberen Muschelkalk des CroKenli iderer Crabens (Osthessen) wurden aus Broekelkalk 4a ('Tro-chitenkalk-Lormation, Kraichgau Subformation; atams-liio/.onc; An is, Oberil lyr) in dor naheren Unigebung von GroKenli ider zahlreiche Lxuvien und Korperfossil ien dekapoder Krebse geborgen. A m haufigsten ist darin Lissocardia silcsiaca v. Meyer,

IS47. YVesentlich seltener sind in dei1

Lossillagerstatte die Cattungen Aspi-do^astcr, Litogaslcr imd Pscadopcm-phix. Das l lachenhafte (mehrere km2), aul eine einzige Lage begrenz-te Vorkommen dei' Lissocardia-\ii\nk vvird als Lrgebnis von populat.ionsriy-namisehen Prozessen gedeutet. Mine Kiklarung aussehlieftlich dureh gun stige diagenetiselie Pro-zesse ist

weniger wahrscheinl ieh. Minvveise auf Baue oder i indere Lebensspuren von Krebsen liegen nielil vor. Das hervorragend erhaltene Material er moglieht erstmals eine vollstandige Besehreibung der Morphologic von Lissocardia imd die sicliere Zuord nung znr I amil ie Nephropidae (O ld nung Ast;ieide;i).

A b s t r a c t

Many exuviae and body fossils of decapod crustaceans have been col-lected in the Upper Muschelkalk of the GroKenli ider Graben (eastern Hessen, Central Germany) . The de-capod bed is a single layer in Brockelkalk 4a (Trochitenkalk-For-mation, Kraichgau-Subformation; atavus Biozone; Anisian, Late lllyri-an) in the vicinity of CroKenliider.

The most common decapod of this fossil lage rstii tie is lissocardia silcsia-ca v. Meyer, 1847. In addition, Aspicio-gastcr, Litogastcr, and Pscudopcmphix occur, although they are much less abundant, in the Lissocardia Bed. The mass occurrence of decapods in this fossil lagei'statte extending over at least, several km2 is interpreted as a result of unusually favorable local

env i ronmenta l conditions rather than as a taphonomie process. Bur-rows or other traces of decapod ac-tivity have not yet been observed. The excellent preservation makes possible the first, comprehensive morphological description of Lisso-cardia and its definite attribution to the family of Nephropidae (order Astaeidea).

Contents

1. Introduction 72 2. The Groftenliider Lissocardia Bed 7:5

2.1 Localities 7 A 2.2 Stratigraphy 7:5 2.3 Sedimontology and paleosynecology 75

.5. Systematic paleontology 7(j 4. Discussion 80

4.1 Systematic position of Lissocardia 80 4.2 Life habit 80

5. References 81

1 Milseo di Sloiia Natiirale, c.so Venezia, - 20121 Milano, Italy ' Miisehelkalkmusenm, Scliloftstraftc 11, l)-74()5:5 lii^ellin^en, (Jermanv • Mailin lAilliei Kinu; Hi, I)-:5(ii:57 (iroKenliidei, (Jermany

71

Alcssandm (iaiassino, I lans I laijdorn f-V Via 111 red Scluil/

1. Introduction Decapod crustaceans, many well preserved in lime-

stone nodules, have been collected from the Germanic Vluschelkalk since the pioneer period of paleontology, early in the If)"1 century. As the first species, the large spiny lobster Paliimnis sucitri was described by Des maiest (1822). Later, v. \le\er (IS40) established the genus Pcmphix for this crustacean, which is most com moil in the Upper Vluschelkalk of Southwest Germany. Until now, it remained the best-known of all Musehel-kalk decapods (Lorster I9(>7). Due to their rarity, other genera of reptant Muschellkalk decapods have been added later: IJlogaslcr by v. Meyer (1844), Lissocardlo by v. Meyer (1847), I'sciidopcmphix by Must (190:5), Clytiopsis by Mill (1914), Aspidogaslcr and I'iralclla by Assmann (1927). A fragmentary carapace has been attributed to I'scud.oglyplica by Lorster (1907), a genus established for Jurassic decapods by Oppel (1801). It was Assmann (1927) who studied the dec apod material housed in major Ger-man collections and discussed their systematic positions and geographical and stratigrapliieal distribution. In his comprehensive study, Lorster (1907) revised the replant, decapods that were then known from Triassic strata worldwide. His monograph clearly demonstrated that the most complete and diverse reptant decapod faunas of the entire Middle Triassic (Anisian, Ladinian) are found in the Upper Miiiitsandstein (Voltziensandstein) of eastern Lrance and Southwest Germany and in the Up-per Muschelkalk of Southwest. Germany. However, the type material of some of the genera listed above has been collected from the Lower Muschelkalk of Upper Silesia (now Poland) and - once again - of Southwest Germany.

Decapod faunas from the Triassic of the Tetliys realm and phylogeny of early Mesozoie decapods have been discussed in a number of papers by Giaessner (comp. Glaessner I?)(>()). In recent years, knowledge of Triassic decapod diversity has been significantly enlarged by sys-tematic investigation of rich conservation iagorstatten, which have yielded decapod crustaceans in Loin hardy and elsewhere, conducted by the Invertebrate Paleontol-ogy Department of the Museo di Storia Naturale di Mi lano. Included in this research programme are the Trias-sic fauna! assemblages of the Ambilobe region (NYV-Madagascar; Garassino cVreruzzi 1995), of Gene (Seriana Valley, Mergamo - N-ltaly; Pinna 1974), of Prati di Kest

(Valvostino, Mrcseia - N-ltaly; Pinna I97(>), of I 'onte Giur inno (Imagna. Valley, Mergamo - N Italy; Garassino t-v Teruzzi I99.i), and of Carriia. ( I Jdine, NL-ltalv; Garassino et al. 1990, (iarassino, in press).

Private collecting activity in many Muschelkalk sec-tions in Germany since publication of Lorster s mono-graph has resulted in a great number of new specimens many of which have been excavated from measured sec (ions and skillfully prepared from hard limestone nod-ules by means of pneumatic chisels. These new speci-mens allow more detailed morphological description of some of the less we'll known genera.and discussion of sys-tematic position. Moreover, they also allow discussion of paleoecology, stratigrapliieal range, and geographical distribution of Muschelkalk decapod crustaceans.

One of the most productive decapod beds yielding an association both diverse and rich in individuals has been discovered by one of us (Manfred Schulz) at the base of the Upper Muschelkalk of eastern Hessen (Central Ger-many) . The most common species in this fossil lager stiitte is llssocardia silcsiam v. Meyer, 1847, hitherto most-ly known from the Lower Muschelkalk from a lew more or less fragmentary specimens. The excellent preserva-tion of relatively complete specimens allows a full mor-phological description o fL i ssoaud ia and confirmation of its attribution to the family Nephropidae Dana, 18,12 (or-der Astacidea Latreille, 180,S). The new specimens of As-pidogastcr and Litogastcr (Glypheidac) , and Pseudopcm phix (Pempl i ic idae) collected in the CroKenl i ider /is.so-cardia Med do not provide additional morphological in-formation. Therefore, they were1 not described in this paper.

The specimens studied in this publication are part of the private1 collection of Manfred Schulz (acronym CSG). Additional material referred to in this paper is housed in the Museum fiir Naturkunde an der Humboldt-Lniver-sitat Merlin (MM), the Staatliches Museum liir Natur-kunde Stuttgart ( SMNS ) , the Musehelka lkmuseum Hag dorn, Ingelfingen ( M i l l ) and in the private collection of M. I lart inger (C I IK ) , Krautheim (Madeii-Wiirttemberg, Germany) . It is guaranteed that none of the figured or re-ferred to specimens will be given to another than a pub-lic collection. The Musehelka lkmuseum Ingelfingen wil l be informed about any change of specimen repository.

72

A decapod crustacean assemblage from Ibe Middle Triassic tipper Muschelkalk of (irolsenliider (I lessen, ( i emiany )

2. The Grofienliider Lissocardia Bed

2.1 Localities lissocardia and ot.lier decapod crustaceans have been

collected in lour outcrops around the town of GroKen-liider near I ulda (Hessen, Central Germany ; Fig. I). Gen-erally, the Muschelkalk in this region is preserved in the GroKenluder Graben, a minor tectonic structure striking SF-NYV. Along this graben, small downfaulted Muschel-kalk blocks a.re quarried for l ime and portland cement. Each of the few localities exposing the section under study has yielded decapod specimens. These localities are: (1) GroKenliider, quarry of Kalkwerk Meister. TK 2:1 Sheet

Nr. 542:] Groftenliider, R :55 :]6 85, H 56 06 (2) Groftenlikler-Miis, road cutting of the Umgehungs-

Mraise Miis. TK 25 Sheet Nr. 542:] Groftenluder, R :U> 08, H 56 06 05

(3) Groftenliider-Miis, landfill of F irma Hil lenbrand. TK 25 Sheet Nr. 542:? GroKenliider, R ,!5 ,H> 11, H 56 05 91

(4) Fulda-Rodges, quarry of F irma Wende. I K 25 Sheet Nr. 542:5 GroKenliider, R 35 43 18, H 56 02 60

In 199*), only Locality 1 is still accessible; Localities 2-4 were only temporari ly open and have1 been refilled.

2.2 Stratigraphy The Lissocardia Bed is a single layer of uniform expan-

sion in the Groftenliider area (Fig. 2). The Kalkwerk Meis-ter quarry ( f ig. :]) exposes a complete profile from the dolomitie mai ls of the Middle Muschelkalk Diemel For-

mation up to the Upper Muschelkalk MeiKner Formation (Hagdorn fr al. 1987: pi. 2). Lithostratigraphieally, it be-longs to the Troehitenkalk Formation (Kraichgau Subfor-mation) at the base of the Upper Muschelkalk Subgroup. Biostratigraphieally, its position is exactly the base of the <7/<7r>//.s-Biozone, which is of Late Anisian (Late l l lyrian) age.

Traditionally, the Gt ' rnianic Muschelkalk is subdivid-ed by a number of isochronous marker beds, many of which can be traced over wide areas of the Muschelkalk basin. In terms of this extremely detailed marker bed stratigraphy, the Groftenliider Lissocardia Bed is a (lis tinct layer in Broekelkalk 4a, 20 cm below the base of Trochitenbank I (Fig. 2, 4). Broekelkalk 4a is a 50-65 cm thick horizon of nodular l imestone (calcilutite, mud-stone,) intorbedded with marlstone. This horizon was originally identified and described as a marker bed some 200 km farther to the South in Baden-YViirttemberg (Southwest Germany ; YViith 1957, Ockert 1992). The same is true for Trochitenbank 1, an 80 em thick set of lime-stone beds (calcirudite, paekslone) with abundant bi-valve and braehiopod shells and eel i inoderm sclerit.es (mostly crinoid columnals, the so-called 1 rochiten).

One layer in Trochitenbank 1 contains shells of Lctra ctiuella IrigoticUa. In the entire 70 to 80 m thick column of the t ipper Muschelkalk, this braehiopod only occurs in this marker" bed, the Tctractinclla-Himk, which can be traced from the Black Forest to the Subhereynian Hills over 500 km in a wide zone along the eastern coast of the Muschelkalk sea (Hagdorn & S imon 199:5). Isochrony of

li'.laslijil Me iKner Format ion

Trochitenkalk--Formation

Musche lka lk Quar ry

F ig . 1. Geographica l position of Lissocardia fossil sites and Upper Musche lka lk outcrop a round ( i roKenl i ider.

Alcssandm (iarassino, Hans I la^ lorn I- Manl ied Schul/.

I ig. I. S l ra l igraphica l posil ion ol l l ie ( i ioKenli idei- Lissocardia Hed and addit ional Lissocardia OCCIII'ICIICCS.

l ig. :}. Ove rv i ew of k a l k u e i k Vleister near (irolsenludei-Vliis vvilli Lissocardia Med ( th in a r row) . T h e M idd l e/Uppe r Vluschelkalk boundary is indi-cated In a (hick arrow.

74

A decapod crustacean assemblage from llie Middle Triassic Upper Muschelkalk of (irolsenliider (I lessen, (iermam )

I ig. 4. Detai l of lissocardia l ied in K a l k w e r k Meis ter ( a r row) .

the Tctradiuclla-Hunk is corroborated biostratigraphieal-ly by the first occurrence of Paraccralites atavas and l\ flcxuosus in the Germanic Basin directly below if, in Broekelkalk 4a (Geisler 19:59, Konig 1920). Thus, the stratigraphical position of the Lissocardia Bod can be ex-actly fixed and easily compared with other decapod oc-currences in the basal Upper Muschelkalk.

J o g y

The lissocardia. Bed is a 5-(> cm thick layer of nodular limestone in the upper part of Broekelkalk 4a (Figs. 2, 4). The nodules containing the crustaceans are irregular, of-ten longitudinal, up to 15 cm long and (i-8 cm wide lensoid bodies of a. grey, micritic, marly limestone. Their l ime content decreases towards the surfaces of the nod-ules and therefore there are no distinct boundaries be-tween concretion and marly matrix. Many of the crus-taceans are positioned close to the upper or lower- sur-face of the nodules, however, others may also be found in the interior' parts of the nodules. The typical preservation

of the crustaceans with carapace and abdomen separat-ed or slightly displaced indicates that most of the fossils are exuviae. Some intact specimens could also have been embedded as carcasses. The three-dimensional and un-compressed preservation of both carcasses and exuviae indicates early diagenetie cementation of the nodules. It is supposed that the early diagenetie cementation of the nodules was triggered by decay of the crustaceans.

W e also discussed whether the nodules originally rep-resented crustacean burrows that were later infilled with lime-mud and subsequently cemented. However, the nodules are not likely to be burrow fills because ( I ) the shape of the nodules is too irregular for crustacean bur-rows, (2) we did not find fecal pellets in the nodules and (:$) because some nodules may also contain actinoptciy gian fish skeletons and are thus definitely concretions formed during decay of an imal skeletons.

The lissocardia--Bed around GroKenli ider yielded the following fossils, most of which are rare:

Braehiopoda: Liugida el. lciiui.ssi.ma I) isdi i is( a dis( o ides

Bivalv ia: Plcuromya muscul.oi.dcs Myophoria vulgaris ludolium disdlcs llocrucsia social is Plagiostoma striatum

Crustacea: Lissocardia silesiaat Lilogastcr oruala A sp id ogas tcrUm ico la Pscudopcmphix 111cyci i

Vertebrata: Act inopter\ gian fish indet.

Crustaceans are the most abundant fossils in the Lisso-cardia Bed. Until Apri l 1999, the four localities yielded the following numbers of decapod specimens: T a b . I : N u m b e r of decapod c rus taceans f rom the ( i ro lsen l i ider L issocardia Hed

Locality 1 2 } 4 Lissocardia silcsiaca 2 t 15 :! 17 lilogaslei oruala I -A.spidogaslcr limitola I I Psetidoprmphix mcyeri. 1 -

\s, On average, one specimen is found per m-. the fossil density is greater (up to five per m-). Below and above the Lissocardia Bed, no crustacean fossils have, been found. A thin tempestitie shellbed a lew cm upsec-tion contains abundant shells of the bivalves Palacouucu la, Myophoria, Ijitolium and the small gastropod .'Xcri I aria or ?Ampulliua. The above faunal list indicates that in the Lissocardia Bed, fossils with ehitinous or phosphat-ic skeletons are over-represented in both abundance and diversity. Among the bivalves, the same is true for genera with calcific shells, whereas genera with originally arago-

75

Alessaiulro (iarassino, I lans 1 las^lorn fr Manfred Seluil/.

nilic shells are rare. Due to early dia.genet.ie cementation of eoquinas with high pore vo lume between the shells, ara.gonit.ic shells have increased fossil potential in tem-pest ite beds. Therefore, the fossil content of the Lissocar-dia Bed and of the ent ire Broekelkalk 4a represents only a small part of the original community. Thus, dia.genet.ic extinction of aragonite shells and diagenetic overprint of the sediment makes it difficult to comment on paleo-ecology and sedimentary environment.

The bent.hic fauna suggests a soft substrate. As there are no elasts or large shells, it can be concluded that the crustaceans must have burrowed in a slightly firm sedi-ment., possibly in a level a few decimeters below the sea-floor. However, there is no definite sedimentological evi-dence for burrowing activity, such as scratch marks or doubtless burrows.

Around Grofseuluder, Lissocardia and the other deca-pod crustaceans are limited to a single layer of Broekel-kalk 4a, however, this layer extends over at least several km2. This striking decapod occurrence can be interpret-ed (1) as an episodic event of extreme population growth or (2) as a short period of time with unusually favorable conditions for preservation of crustacean skeletons. Giv-en the second case, the decapods inhabited the Muschel-kalk seafloor over longer periods and their skeletons usually were dissolved by diagenetic processes. W e favor the first inference and explain the mass occurrence as an explosive local or regional population increase. In the Muschelkalk, episodic mass occurrences of fossils also have been describe,d from ophiuroids, asteroids, and bra-chiopods. Aspiclogaster also occurs hundreds of kilome-ters distant in the same horizon at Neidenfels, Baden-W u r t t e m h e r g ( M i l l 1031).

The marl layers of the Hassmersheim Subformation

(which follows upsection and which are very similar in fau-na and sediments) yielded Aspidotfasler, liloi>aslci and rare lissocardia and Pscudopcmphix. Localities are Lschelbronn. Baden-VViii'ttemberg (Konig 1920), Kiinzelsau and Neiden-fels, Baden-Wurttemberg ( M i l l 1477, 7S7), Rottershausen, Bavaria (MH1 107:5), Troisledt, Thuringia ( M i l l l(>! I. CI IK 22017, 2201!)). Aspidogastcr and Pscudopcmphix have also been recorded from the upper part of the Trochitenkalk formation and from the MeiKner formation (romp. Ass-mann 1927, Lorster 1907). However, lissocardia has been previously recorded from the Upper Muschelkalk only in one specimen from the shaft of the. Lriedriehshall salt mine ( S M N S 4401/058, Alberti-Collection). These records in different strata indicate that the decapods inhabited the Muschelkalk sea over a longer period. Lpisodical events of mass reproduction may have1 caused local or regional mass occurrences such as the Crolsenluder Lissocardia Bed.

The Kraichgau and Hassmersheim Subformalions of the Trochitenkalk formation are characterized by stacked parasequences (or high frequency sequences, comp. Aign cr & Bachmaun 199:5). The t hickly bedded limestones such as Troc.hit.enhank 1 are interpreted as transgressive peaks din ing high sea levels and (heir stenohaline ccliinoderms and articulate brachiopods are exotic immigrants from Tethys (Hagdorn ik Simon 199:5). The marlstone and nodu-lar limestone intercalations such as Brockelkalk 4a or the three marlstone horizons of the Hassmersheim Subforma-tion were deposited during low sea level and increased in-put. of fine elastics. Decrease of echinoderms in these hor i-zons might indicate salinity changes that were tolerated by the decapods. The, Troehit.enbanke have not yielded de-capods because the coarse skeletal beds were unfavorable for crustacean preservation.

3. Systematic paleontology Order Deeapoda Latreille, 180:5 Infraorder Astacidea Latreille, 1803 Lamily Nephropidae Dana, 18.52

Genus lissocardia v. Meyer, 1847

1847 lissocardia - v. Meyer: 575 1851 lissocardia v. Meyer - v. Meyer: 254 190.5 lissocardia v. Meyer - Wi ist : 11 1927 lissocardia v. Meyer - Assmann: 335 1927 Piratclla n. gen. - Assmann: :5:57 19:50 lissocardia v. Meyer' - Beuerlen & Glaessner: 53 19:50 Pi raid la Assmann - Beuerlen & Glaessner: 5.5 19:50 lissocardia v. Meyer - Beuerlen: :520 1930 Piratdla Assmann - Beuerlen: 320 1907 Lissocardia v. Meyer - l or ster: 174

7(>

The genus Piratclla has been established by Assmann (1927) because of alleged lack of eristae on the gastrieal region and a shallow abdominal notch, however', lie em-phasized its similarity with Lissocardia. l orster (1907) treated Piratclla as a synonym of Lissocardia. The new material corroborates Lorster's decision. Gone ro t ypo : lissocardia. siicsiaca v. Meyer, 1847 D iagnos is : Carapace cylindrical, relatively high, com pact. Rostrum narrow. Longitudinal dorsal keel with spines from rostrum to the posterior margin. Cervical groove deep, gastroorbital groove short. Post.eervieal groove weaker than branehiocardical groove, dorsallv strongly reduced, becoming deeper downward complete-ly separating the posterior, reduced part of the hepatic,al region. Anter ior' part of the hepatical groove horizontal, appear ing only in outlines. Gastrieal region with two

A decapod crustacean assemblage from llie Middle Triassic Upper Muschelkalk of (irolsenliider (I lessen, (iermam )

longitudinal carinas. Second carina on anterior side strongly hent. upwards towards the rostrum. Antennal re-gion on anterior side constricted by a depression origi-nating from the antennal groove. Keel and carinae with spine,s, posterior antennal region and cardieal region with coarser granules, otherwise uniform granulation. Abdomen weakly ornamented; epimeres separated from teigum by granulated longitudinal bulge. Pereiopod I with elongate merus, short carpus and strong propodus, chelate, elongate index and daetylus with long, dagger-like spines on opposite internal edges. Pereiopods II and 111 chelate. Pereiopods IV and V with terminal daetylus. Extended diagnosis modified after Eorster (1967).

Lissocardia silcsiaca v. Meyer, 1847 f igs. ,1-10 1847 Lissocardia silcsiaca - v. Meyer: 575

Lissocardia magna - v. Meyer: 575 Lissocardia silcsiaca v. Meyer - v. Meyer: 254, Taf. :Y2, Eig. :$4-:J!>, 37-iW Lissocardia magna v. Meyer - v. Albert i: 196 JAssocardia silcsiaca v. Meyer - lick: 108 Lissocardia silcsiaca x. Meyer - Assmann: TUi, Taf. 8,1-ig. 4-8, Taf. 13, f ig. I Piratclla badcnsis n. gen. no. sp. - Assmann: T58, Taf. 8, Eig. 2-W Lissocardia silcsiaca v. Meyer - Schmidt : :>I8, Eig. 874 Piratclla badcnsis Assmann, 1927 - Schmidt: :>I8, Eig. 875 P. badcnsis Assmann, 1927 - Glaessner: :>I7 Lissocardia silcsiaca v. Meyer - Assmann: 110, Taf. 22, Eig. 6-8 Lissocardia silcsiaca v. Meyer - Glaessner: 40, fig. 18, I Lissocardia silcsiaca v. Meyer - Eorster: Kit), Taf. :!6, f ig. I lissocardia silcsiaca v. Meyer - Eorster: 175, Taf. 9, Eig. 6; Eig. 14. Lissocardia. badcnsis (Assmann, 1927)- Eorster: 176

1847 1851

1864 1865 1927

1927

1928

1929

1929 I9;'.7

I960

1965

1967

1967

, fig. :!/ (same speei-ig. 6-7) Museum fur

/LI Berl in

I Autotype: v. Meyer 1851: Taf. men as Assmann 1927: Taf. 8, Naturkunde an dei" Huinboldl-Universitat MB.A. 9:J6. Locus typ icus : Tarnowitz, Upper Silesia (now Tarnowskie Gory, Poland), abandoned Bohm quarry. S t r a t u m typ icun i : l o w e r Muschelkalk, upper pact of Karehowice Eormation (Anisian, liarly lllyrian). G e o g r a p h i c a l occur rence : l o w e r Muschelkalk: t ipper Silesia (Poland), Brandenburg (East Germany) , Baden YViirttcmberg (Southwest Germany) . Upper Muschel-kalk: Baden-Wurttemberg (Southwest Germany) , lies-sen, Thuringen (Central Germany) .

Fig. .1. Lissocardia silesiaat \ . (ion in dorsal view.

Meyer, IS 17. Tail fan reconsduc

-TW-yrv, r

Fig. (>. Lissocardia silxsiaca v. Meyer, IST/. Reconstruction.

Fig. 7. Lissocardia silcsiaca v. Meyer, IS 17. Specimen CSC l/l. Carapace, pereiopods and antennulae of a large specimen; e\u via, right side, lateral view. \ 1.5.

77

Alessaiulro (Jarassino, I laus I la,i{(lom fr Manfred Seluil/

A decapod crustacean assemblage from llie Middle Triassic Upper Muschelkalk of (irolsenliider (I lessen, (iermam )

Strat igraphical occurrence: Lower Muschelkalk, Jena Formation, Freudensfadl Formation, Karehowice For-mation (Anisia.ii, Bithynian to Farly lllyrian); Upper Muschelkalk, Trochitenkalk Formation (Kraichgau Sub formation, Broekelkalk 4a and contemporaneous Troi-stedt Suhformation), atacas Bio/one (Anisian, Late lllyri-an). Material : The originals of Lissocardia (MB.A. 9;iti, 9:>7) and Piratclla from the Lower Muschelkalk have been so carefully described by Assmann (1927) and Forster (I9b7) that a restudy was not necessary. The same is (rue for the specimen mentioned by v. Alberti (IS(j4: I9(>) from the Upper Muschelkalk of Friedrichsha.ll ( SMNS 4401/().r)S). Due to (heir poor preservation, a number of very fragmentary and compressed Lissocardia speci-mens from the Lower Muschelkalk Freudenstadt. forma-tion (Fewer Anisian) of Altkrautheim (Holienlohekreis, Baden-YViirttemberg) in M. Hartingers collection (C I IK 220:,)()-22042) have not been studied in detail. The same is true for a typical Lissocardia chela from the Lower Muschelkalk Jena Formation of Riidersdorf (Branden-burg, Fast Germany); YV. Toiiiovv (Berlin) kindly sent a photo of this specimen in his private collection (uneata-logued). However, these specimens provide additional data 011 stratigraphieal and geographical range of the species. A fragmentary specimen (carapace, chela) from the lower Muschelkalk Jena, formation of Buehen-Bodigheim (Mi l l 1074) is much better preserved. Among 59 more or less complete and well preserved specimens from the GroKenluder Lissocardia Bed, 17 have been se-lected for study. After skillfull preparation, they are visi-ble either in lateral or in dorsal view. Certainly, most of the specimens are exuviae showing the typical separa-tion between carapace and abdomen. Two specimens (CSC 2/2, CS(; 4/4) are lull body fossils. An additional specimen from the Trochitenkalk Formation ('Troistedt Sublormation, atm'us Bio/one) of Troistedt (Thiiringen) in M. Hartingers collection (C I IK 22019) has also been studied.

The excellently preserved specimens from Giofsen liider make possible for the first time a lull morphologi-cal description of Lissocardia silcsiaca, which was known before by a few fragmentary specimens only. Description: Lissocardia silcsiaca is a medium-sized astacidean of 4 to (» cm length, with a coarsely tubercu-late ca.rapa.ee and strongly elongate index and daetylus of chelate pereiopod I. Ca.ra.pacc: In lateral view in almost all specimens, the carapace has a subreetangular shape, which becomes slightly more narrow towards the anterior margin he-

cause ol the slight curvature of the ventral margin. Over its total extension, the straight dorsal margin forms a crista with a row of equal-sized spines pointing forward. The rostrum is short, without supra-and subroslral teeth and with a pointed distal extremity. The posterior mar-gin is sinuous and strengthened by a strong marginal ca-rina with a row of spines in its upper part. The ocular in-cision is narrow and shallow and the antennal and plery-gostomial angles are not very marked. Two strongly barbed carinae extend along the antennal region of the carapace, joining together at the base of the rostrum. Moreover, the surface of the carapace has deep cervical and branchiocardic grooves with exterior margins orna-mented by rows of equal-sized spines. Generally the largest part of the carapace is smooth; strong spines are located only near the grooves, and small tubercles are lo-cated near the carinae. Abdomen: The subreetangular somites are equal in length. The triangular pleurae are strengthened by a coarse tuberculate transverse4 median carina, and the margins have a row of similar small spines. Somite VI has a subreetangular shape and is slightly longer than the others. The telson (f ig. 5) has a triangular shape with a rounded distal extremity; it is strengthened by two thin median longitudinal carinae. The uropods have the same length as the telson. The exopodite, with rounded diaeresis, is crossed by a strong median longitudinal cari-na. The median carina crossing the endopodite longitu-dinally bifurcates at its anterior extremity. The surface of the abdomen and of the tail fan is slightly tuberculate. Ccpl ia l ic appendages: None of the specimens has the eyes preserved. The antennular peduncle is composed of three arlieola: the 1° and the 2° are thin and elongate, and the :>° is short and stocky ; two long flagella art' artic-ulated with it. The antennal peduncle is composed of three thin and elongate art.icula. The flagellum is twice the body length. The scaphoeerite is not preserved. Thorac ic appendages: The maxilliped III is composed of thin, elongate and barbed art.icula. Pereiopod I has an elongate merus, short and stocky carpus and strong propodus with strongly elongate and curved distal ex-tremity of daetylus and index (Fig. N). The interior mar-gins of the daety lus and the index have alternating strong and small teeth. Pereiopods ll-lll are chelate. I lie exteri-or margins of pereiopods I III have sparse and strong spines. Pereiopods IV-V have a terminal daetylus. Abdomina l appendages: The pleopods have a subreel-angular sympodife; two long multiarticulate flagella are attached to the sympodife.

9

Alessandro (Jarassino, Hans I la^dom & Manfred Seluil/

4. Discussion

4.1 Systematic position of Lissocardia

In his revision of the Triassic replant, decapod crus-taceans, l orster (1907) emphasized the most important characters of lissocardia: subrectangular carapace, dor-sal margin of carapa.ce with a longitudinal keel with spines from rostrum to the posterior margin, deep cervi-cal and branchiocardicaI grooves, antennal region with two longitudinal car inae and pereiopod I chelate with strongly elongate dactyl us and index. These features could be found in the examined specimens.

Due to the fragmentary preservation of v. Meyer's specimens, the systematic position of Lissocardia has been controversial for a long time. Assmann (1927) as-cribed Lissocardia to the Ncphropsidea whereas l orster (1907) compared it with the Clypheidae Zittel, 1885, the Lrymidae van Straelen, 1924, and the Pemphic idae van Straelen, 1928, and stated its intermediate position be-tween these families. Glaessner (1909) ascribed this genus to the family L rymidae van Straelen, 1924 (sub-family Clytiopsinac Beurlen, 1927).

The complete and perfect preservation of many of our specimens made possible a more precise statement of its systematic, position. Certainly, Lissocardia. is not an erymid because this family has a cyl indrical carapace, cerv ical and branchiocardieal grooves devoid of spines and a pereiopod 1 with short and stocky chelae. Lissocar-dia has a longitudinal keel with spines in the dorsal mar-gin of the carapace, longitudinal car inae in the antennal region and long and strong chelae of pereiopod I. This character is diagnostic enough to exclude an ascription of Lissocardia t.o the family Lrymidae.

Zariquiey-Alvarez (1908:199-201) and l lolthuis (1991: 19) pointed out the main characters of the family Nephropidae Dana, 1852: subrectangular carapace, lon-gitudinal keel with spines in the dorsal margin of cara-pace, tuberculate longitudinal car inae in the antennal region, deep cervical and branchioeardical grooves, ab-dominal somite with a transverse median carina and pereiopod I with elongate and strong chelae with long and small teeth along the interior margins of dactyl us and index. Because these characters are clearly devel-oped in the studied specimens we ascribe the genus Lis-socardia. t.o the Nephropidae.

Two species of Lissocardia have been established from the Muschelkalk: L. silcsiacax. Meyer, 1851 and L. magna v. Meyer, 1851, both of them from the Lower Muschelka-lk karchowice Formation of Upper Silesia. They only dif-

fer in size and are certainly conspeeific. Lorster (1909) al-so assigned the poorly known Piratclla badcnsis Ass maim, 1927 to Lissocardia. I lovvever, he kept, this species, which is based on two compressed specimens ( Lower Muschelkalk, South Baden, Southwest. Germany) , as a separate species because lie could not decide with cer-tainty whether or not its diagnostic characters (shallow abdominal notch, no cristae on the gastrieal region) are only a matter of poor preservation. A specimen recently collected in contemporaneous Lower Muschelkalk stra-ta of Buchen-Bodigheim (northern Baden; M i l l 1074) has typical cristae on its gastrie al region and does not substantially differ from Lissocardia si.lcsiaca in the shape of the the abdominal notch. Therefore, we do not hesitate to treat Piralclla badcnsis as a junior sy nonym of Lissocardia silcsiaca.

4.Z Life habit The small si/.e of Lissocardia with its slender carapace

and abdomen and its elongate and strong chelae give ev-idence that, like other astaeideans, if was a benthie cms tacean burrowing in muddy or slightly consolidated sedi-ment. Its long and slender chelae with daggar-like spines on the interior edges of index and da.ct.ylus indicate food gathering specialization. However, the low diversity of other invertebrate fossils in the GroKenli ider Lissocardia Bed does not indicate any kind of specialized predator-prey relationship. Lissocardia can be compared to the ex-tant astaeideans Thaumaslochclcs and Acanthacaris that live as borrowers on muddy bottoms and have chelae similar to those of Lissocardia (Llolthuis 1991).

A c k n o w l e d g e m e n t s W e gratefully acknowledge the permission to study

addit ional specimens of Muschelkalk decapods kept in the private collections of Michael l lart inger (Altkraut-heini) and We rne r Tornow (Berl in) . The artwork of Ligs. 5 to 10 was done by Franco Nodo. Manfred Schulz grate fully acknowledges permission for collecting in the quar-ries of the Ka lkwerk Meist.er, Ste inbruch Wende and in the Lrddeponie Hi l lenbrand. Dr. Lrika Lietrzeniuk, Berl in, and Dr. Max Urliehs, Stuttgart, provided informa lion on typo and figured material . W e thank Dr. Daniel Blake, Urbana, who kindly improved the Lnglish phras-ing, and Dr. Giorgio Teruzzi, Milano, for his useful advice and for careful revision of the text.

80

A decapod crustacean assemblage from llie Middle Triassic Upper Muschelkalk of (irolsenliider (I lessen, ( i e rmam )

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8 1