Rivìsta Italiana di Paleontologia e Stratigrafia pagine 143-i66 TAXONOMY, STRATIGRAPHY AND PHYLOGENY OF THE NE\T GENUS LANCEOPTYCHITES (AMMONOIDEA, ANISIAN) MARCO BALINI Receìoed February 10, 1998; accepted ApriL 3, 1998 Key-zuords: Ammonoidea, Population analysis, Triassic, Ani- Damit kann bewiesen werden, dafl das Auftreten einer subakuten./fa- sien, Biostratigraphy, Phylogeny, Northern Alps, Southern Alps. stigaten Externseite unci eines lanzettfórmigen \'Vindungsquerschnitts wlhrend des lVachstums, bei flachen Ptychitidae, eine normale onto- Riassunto. Viene effettuato per la prima volta uno studio po- genetische Entwicklung darstellt und dass es sich dabei nicht um 'Va- polazionistico degli Ptychitidae compressi (Ammonoidea) raccolti chstumsanomalien handelt, wie rnanchrnal rn der Literatur vermutet strato-per-strxto nel Calcare dr Prezzo (Anisico superiore, Alpi meri- wurde. Ammonoideen mit einer solch eigentùmlicher Ontogenese dionali). Si dimostra come in alcune popolazioni di Ptychitidi com- werden nun aus der Gattung Flexoptychites, zt d.er nur noch flache pressi durante I'ontogenesi si possa verificare una modificazione del Ptychitiden mit gerundeter Externseite gerechnet werden, ;rusgeglie- ventre, che diventa subacuto/Íastigato mentre la sezione deì giro di- den und zur neuen Gattung Lanceoptychìtes gestellt. Die neue Gat- venta lanceolata. Questo particolare sviluppo della zona ventrale non tung ist eine sekundàre Abspeltung von F/exoptychires und umfasst è dovuto ad anomalie di crescita, come talvolta riponato in letteratu- zur Zett aus vier Arten: Lanceoptycbites telox sp. n, (Typusrrt), l sryx ra, ma è un normale sviluppo ontogenetico. Gli Ammonoidi con que- sp. n., l. indistinctus (Mojsisovics, 1882) und L. cbarlyanus (Diener, sto tipo particolare di ontogenesi sono separati dal genere Flexoptychi- 1900). Z. sllx und seine peramorphe Abspaltung L. telox sind strato- res, che comprende quindi gli Ptychitidi compressi con ventre arro- phenetische Arten aus dem Prezzokalk, wo sie auf den rnittleren tondato, ed inclusi nel nuovo genere Lanceoptychies. Il nuovo genere Abschnitt der Zone d.es Paraceratites tìnòdosus (Illyr) beschrànkt è un discendente secondario di Flexoptychites e cornprende 4 specie: Z. sind. Úber L. indistinctus (Mojsrsovics, 1882) und L. charlyanus (Dte- uelox (tìpo) sp. n., Z. irlx sp. n., L. indistinctus (Mojsisovics) e Z. ner, 1900) gibt es keine gesichenen stratigraphische Angaben. Diese cbarlyanus (Diener). L. styx ed il suo discendente peramorfico L. veLox beiden Morphospezies werden anhand des Typenmaterials revidien. sono specie stratofenetiche. Entrambe le specie sono istituite su mxte- riale proveniente dal Calcare di Prezzo, dove sono limitate alla pane media della zona a Paraceratites linocJosus (Illirico). L. indistinctus (Mojsisovics) e L. charLyanus (Drener) vengono rivisti sulla base dello Introduction: summary of the knowledge on the west studio dei tipi. Poìchè non è disponibile nessuna informazione sulla tethyan Ptychitidae. distribuzione stràto-per-strato dei tipi, questi taxa restano semplici morfospecie. The family Ptychitidae Mojsisovics, 1882 is a typi- cal component of the open marine ammonoid assembla- Abstract. For the first time a population analysis of compres- ges during Anisian and in part Ladinian times. It groups sed Ptychitidae (Ammonoidea) bed-by-bed collected from Prezzo Limestone (Upper Anisian, Southern Alps) is perforrned. The analy- leiostraca ammonoids with depressed to compressed coi- sis allows to derlonstrate that s'ithin some populations of compres- ling and a typicai ammonitic suture line. The family is sed ptychitids during the gros/th the venter may become subacute/fa- common in the Arctic, Pacific and Tethyan paleobiopro- stigàte and the section lanceolate. This modification is not due to vinces, while its episodic occurrence in epicontinental growth anomalies, as sometimes belieted in Ìiterature, but is a nor- rnal ontogenetic detelopment. The ammonoids with this peculiar on- seas (Upper Muschelkalk: IJrlichs Er Kurzweil, 7997) is togeny are moved from the genus Flexoptycbites, that groups the corn- not surely related to living populations, but could be pressed ptychitids with rounded venter, into the new gents Lanceop' due to post-mortern drifting of the shells from the Tethys tycbites. The new genus is a secondary descendent of Flexoptychites (Urlich Mundlos, 1985). During the Pelsonian-Illy- and comprises 4 species: L. velox (type) sp. n., L, styx sp. n., L. indi' & stinctus @lojsisovics) and L. cbarlyanus (Diener). L, styx znd its pera- rian (Anisian) the family is represented in the \flestern rnorphrc descendant L. veLox are stratophenetic species. They are de- Tethys by the genera Ptychites Mojsisovics, L882, Flexop- scribed from the Prezzo Limestone, where they are confined to the tychites Spath, 1951 and Malletoptychites Diener, 1916. middle part of the Paraceratites trinodosus zone (Illyrian). No bed-by- rare and restricted red lime- bed information is availabie f.or L. indìstinctzs (Mojsisovics) and I. The last genus is to nodular charLyanus (Diener). These morphospecies are revised on the basis of stones, whrle Ptychites and Flexoptychites are much more the type rrrterial. frequent and reiatively facies-indipendent. Repre- sentatives of Ptycbites and/or Flexoptycbites are very Zusammenfassuzg. Anhand von horizontiert aufgesammelten red nodular limestones (i.e., Schreyeralm Fossilfolgen aus dem Prezzokalk (Sùdalpen), wird fùr flache Ptychiti- abundant in dae (Ammonoidea) erstmals eine Populationsanalyse durchgefiihn. and Han-Bulog Limestones), but they can also be found Dipanimento di Scienze della Terra, Università degli Studi, Via Mangiagalli 34,20133 Milano, Itely; ernail: [email protected] M. Balini FiO I Location map of the nost lmpoftant Anisran localities of Southern and Nonhern Al." -^.,;^--r ;- .r"- f--, The analysis of the taxo- nomicrl position oI Lhese species is complex. Most of the pro- blems stem from the old techni- ques oi collect ion. I n rhe p"rsr \trrarttr//-';.1' i-LrI .1".1..rLltq ldJt lqrrrLrr)/^^.r,,..r\ rh"('r! specimens were not collected with special càre on rhe posirion in the stratigraphic sections. On the opposite,.rll rhe specimens coming from the same lithology (roughly the same formation) were grouped together into the same "assemblage" which was ac- tua1ly far from a true natural as- soci.rtion. As l consequence the type series of rhe new species were not composed after the analysis of ontogeny and mor- in black or brown - bituminous limestones (r.e., Prezzo phoiogical variability within true populations of indivi- and Gutenstein Limestones), in sandy/silty limesrones duals, but they were artificially assumed. At the presenr (i.e., Dont Formation) and in siliceous nodular lime- no good information on the stratigraphic relationships stones (i.e., Buchenstein Formation). between the type specimens of these species is available. Despite the frequency in the stratigraphical record Therefore the problem of the understanding of the mor- and the wide paleogeographic distribution, Ptycbites and phological features intermediate between different spe- FLexoptycbites, as the resr of the family Ptychitidae, are cies cannot be solved because, the chronological and far from being well known. The history of the know- biological meaning of their relationships is unknown. ledge of the group is long and complex. Ptychites was All of these problems are common with Triassic ammo- {ormallzed by Mojsisovics in 1875, and in a few years noids (Tozer, 1971), however in the case of Ptychitid.re the genus grew including more and more species nota- they are especially severe because rhe raxonomy of this bly diverse in whorl section, coiling, size and surure family is much more influenced than that of other line. The wide variety of species attributed to Ptychites groups (i.e., the famrly Ceratitidae Mojsisovics, 1879) by vu.as remarked by Mojsisovics (1882), who distinguished collection from Anisian condensed red limestones within the genus several groups of species. Flowever the (Schreyeraim and Han-Bulog Limestones), where three to genus continued growing, and it gradually became a ta- four ammonoid zones are surely represented (Gaetani, xonomical basket, so large that in the Fossilium Catalo- 1969, p.492). gus 84 species were counted (Diener, 1915). Afterwards The only way to solve these complex and inter-re- the content of that basket was gradually reduced by re- lated taxononical and stratigraphical problems should moving the most diverse species creating new genera, so consist in the application of bed-by-bed (population) that the taxonomy was shifted: the former genus Ptychi- analyses to fossil-bearing sequences (stratophenetic .rp- tes became a family composed by most of the previous proach s.1.: Gingerich, 1,979; Dzlk, 1987) possibly corre- groups of species raised to rank of genera. Much later sponding to historical localities. This paper shows the (Tozer, 1981) moved Discoptycbites Diener, 1916 (:Mo- first result of the attempt at applying this technique ro jsisovics' group of P megalodiscus) to the family Sturii- the Ptychitidae of two Illyrian sections of the Giudica- dae Kiparisova, 1958. IJnfortunately this reorganization rie (Southern Alps). did not involve all the species formerly attributed to Pty- chites, bur only the more frequent and morphologically The new data from lhe Southern Alps. "extreme" forms. Several species, sometimes rare, often ba- sed on very few or single specimens, usually