LOMBARDO, CRISTINA

MANAROLLA, GIANLUCA

MANENTI, MATTEO

RENESTO, SILVIO

TINTORI, ANDREA

VENDICO, MASSIMILIANO

English

Riviste UNIMI

Rivista Italiana di Paleontologia e Stratigrafia volume luz numero 1 pagrne 131 134 Aprile 1996NOTE BREWAN EXCEPTIONAL REPTILE FIND IN THE NORIAN (LATE TRIASSIC)LAGERSTÀ.TTE OF ENDENNA (ZOGNO, BERGAMO, ITALY)ANDREA TINTORI, SILVIO RENESTO, CRISTINA LOMBARDO, GIANLUCA MANAROLLA.MATTEO MANENTI & MASSIMILIANO VENDiCOK^,-",,^.).. p--r;li. Norian (Late Triassic), Calcare di zorztno,Lombardy Q.tronhern Italy), new find.Riassunta" Durante un sopralluogo nella località di Endenna(Zogno, BG) il 5.10.95 è stato rinvenuto un frammento di un granderettile parzialmente danneggiato da scavatori abusivi. Dopo il salva-taggio del blocco già isolato, si è proweduto alla ricerca e al recuperodella rimanente pane dell'esemplare. Durante questi lavori sono an-che stati sorpresi alcuni scavatori abusivi che sono stati segnalati allacompetente Soprintendenza. Il rettile si presenta completamente in-globato in matrice calcarea molto tenace e si prefigura parzialmentearrotolato e con il cranio disarticolato rispetto al resto del corpo. Lahnghezza totale supera i 4 m e 1o stato di conservazione è da ritener-si ottimo. Sulla base di osservazioni preliminari si può ipotizzare 1asua àppar-tenenza all'ordine Thalattosauria. Si tratterebbe quindi delpitì grande rettile acquatico triassico, con I'esclusione degli ittiosauri,finora conosciuto.Abstract. Durìng a survey àt the fossiliferous site of Endenna(Zogno-Bergamo) of Norian age, a huge reptile has been found at Oc-tober the 5th, 7995. The recovery of the whole specimen took place atthe beginning of November. Four main blocks, plus minor fragments,are now in the laboratory of the Department of Eanh Sciences of theMilano University waiting for the long prepararion. The specimen issomewhat more than four meters long, the head being disarticulatedin front of the body. A preliminary survey suggesrs the reptile maybe ascribed to Thalattosauria. thus, apart from the ichthyosaurids, itwould be the largest marine reptile of the Triassic.The find.The fossil-site of Endenna (Zogno, Bergamo, Italy)is one of the most important sites in the Calcare di 7nr-zíno (Zorzino Limesrone) (Tintori et a1., 1985). Viththe permit of the Soprintendenza Archeologica dellaLombardia and under the direction of the senior author,field-works were carried our from 1978 unttl 1983,when works v/ere stopped for logistic causes and startedin the nearby Zogno2 locality. Nonetheless, regular sur-veys are necessary because private collectors frequentlydamage the site, anything but exhausted. A couple ofthem have been catched during the recent works andreported to the competent aurhority.Hundreds of fishes have been collected during sixyears of digging (Beltan & Tintori, 1980; Tintori, 1980,198t, 1983, !99Q, 199L, 1992, 1995; Tintori & Renesro,1983; Tintori & Sassi, t992), together wirh some reptiles(Padian, 1981; Pinna, 1,979,1,980, 1984;Pinna 6c Nosot-ti, 1989; Renesto 1.984, 1992, 1,993,1994a,b, c, t995a,b;Renesto & Tintori, 1995) and several, mostly undescri-bed, invertebrates (Basso & Tintori, 1994).On the last 5th of October, the senior author wasaccompanying Dr. W. Bausch (Erlangen, Germany) to asurvey for geochemical sampling in Endenna. He founda block, measuring about 80x40 cm (block n.3) whichshowed remains o{ a very large organism, possibly a rep-tile. Coming from level 11 (Tintori et al., 1985), theblock had been removed and damaged by unauthorizeddiggers. In this case, splitting was difficult because thebig fossil has disturbed the regular lamination and hascaused a locally stÍonger cementation. The relative position between the block and the resr of the layer wasdifficult to state, but the possibilities that at leasr part ofthe fossil rvas stiil in place were good. The problem wasthat the find was close to the end of the fossilleveloutcrop, so we wondered how much of the fossil hadbeen already destroyed by natural erosion.The block was taken to Milano only a few dayafter and, by the end of October, we organized the reco-ver of the rest of the fossil. It rook rwo davs of work(the 3Oth of October and the 2nd of Norre-t".) for sixpeople, but we had the greatest expected success: the re-main of the reptile was still in place and could be com-pletely removed.Closely observing the front of layer 11, we couldsee that the reptile was in its lower parr. The upper part'was then removed; the underlying thin, shaly levelmade the rest of the fossiiiferous level easy to take off.Taking advantage oÍ a lateral small karstic canai (KC inFig. 1) and natural fractures the caudal region (Fig. 2)Milano, via Mangiagalli 34,2a1.33 Milano, Italy.- Dipanimento di Scienze della Terra dell' Università degli Studi di132 A. Tintori, S. Renesto, C. Lombardo, G. ManaroLla, M. Manenti & M. Vendicoll{{has been evidenced on the upper surface of a slab (Fig.1;block +) measuring about 140x105 cm. The rest of thefossil was more problematic to recover: the fracture be-tween blocks 2 (60x50 cm) and 1, (75x30 cm) was irregu-lar, leaving a couple of small fragments in between. Onthe whole, the reptile has suffered very little damage.The total weight of the blocks is about 250 kg; theyhave been trasported for about 1 km on hand-barrow upto the car.Shape and dimension of the skeleton can be gues-sed trough the sediment covering the fossil. A part ofthe posterior leg (knee arriculation) has been alreadyprepared, to help in a preliminary classification. The ob-servation of the fossil suggesrs that the reprile has longtrunk and tail, relatively short legs and considerablylong skull. Its total length should be more than 4 m.The body, lying on its belly, forms an almost completecircle (Fig. 1). All these features indicate the skeletondoes not belong to an ichthyosaur; in fact, femur, tibiaand fibula, showing sharp epiphyses and narrow diaphy-ses, are very different from those of Ichtyosaurs. On thebasis of the same morphologic features we can excludethe fossil belongs to the nothosaurs, which have shorrertail, longer neck and smaller skull. Leaving apan rheichthyosaurs, to nothosaurs belonged the largest knownacquatic reptiles in the Triassic, before this find. A spe-cimen of Paranothosaurus atnsleri from the Ladinian ofMonte San Giorgio (Canton Ticino, Switzerland) rea-ches 3.80 m and it was the largest one, as far as weknow.Triassic phytosaurs seem to show more similaritieswith the new find. They are crocodile- like archosaurswith nostrils back near the eyes. Phytosaur remains areknown from Upper Triassic in Germany, in USA and inIndia and fragments are found also in several sires of theMiddle and Far East. Phytosaurs are thought ro havedwelled in continental environments, such as lakes andalluvial plains, and to have very rarely visited mariney/aters. This is clearly in contrasr with the fossilizationenvironment of the Caicare di Zorzíno, which is an in-traplatform basin with only small islands nearby (|adoulet a1., 1994; Renesto & Tintori, 1995; Tintori, 1995).Nonetheless, an isolated skull of a phytosaur had beenalready found in Endenna, but it is probably a fragmenrof a floating skeleton coming from dry land (Renesto,1995b). The new specimen cannot have been transpor-ted: its skeleton is complete and perfectly articulated,apart from the skull. Moreover, though the relative di-mensions of the skull are comparable to those of phyto-saurs, other features have different proportions: tail, forexample, is too long. Only a last group of reptiles canbe compared with the new, large specimen: Thalatto-saurs. These are possibly archosauromorph reptiles char-acterized by relatively short legs and long, laterally com-pressed tail.Thalattosaur remains are known from the MiddleTriassic of the Formazione di Besano (Grenzbitumenzo-ne for the Swiss authors) and of California and from theUpper Triassic of British Columbia. Aiso Endenna haveyielded two specimens of Endennasaurus (Renesto, 1984,1992). Thalattosaurs lived in strictly marine environ-ments (fossils are often associated with ichtyosaurs andammonites) and they likely had a semi-durophagousdiet. Proportions of the new reprile are well comparable\*"\Fig. 1 - Schematic draw of the four blocks with the probable repti-le outline (dotted area, in black the already exposed poste-rior leg) as seen from above. KC: karstic canal; S: slum-ping like deformation of the underlying laminae besidethe specimen belly; striped area: empry region.We expect the preparation will rake a very longtime: on the lower side, apparently the easiest, at least18 months are necessary to expose the bones. Flowever,it will be convenient to expose the fossil on both sides,at least in important parts, because it is fortunately veryslightly compressed; even the head is tridimensionallypreserved. 3D conservation is rarely found in our No-rian locaiities and only regards parts of large specimenswith strong structures (the skull of Mystriosuchus andthe mouth region of large Sargodon tomicu). Normally,fossils are totally flattened and bones are more or lessbroken by lithostatic pressure.Taphonomic and systematic remarks.The impact of the reptile body on the bottomcompressed the underlying laminae, inducing also a uni-derectional slumping-like deformation for at least 1 mfrom the body itself (S in Fig" 1); this fa*, togetherwith the absence of further compression of the skeleton,suggests that diagenesis in this level has been remarka-bly early. Laminae in fact, show folds which keep theirindividuality. An accurare sedimentological-geochemicalstudy on those laminae is trying ro undersrand the firstdiagenetic stages in an anoxic environmenr with predo-minant carbonatic sedimentaticn.Exceptional repttle find tn EndennaFig. 2 - The slab (block 4 in fig. 1) with the tail. Scale-bar: 15 cmto those of thalattosaurs and their life environment is inagreement with the paleoenvironmental reconstructionof the Calcare di Zorzrno.In conclusion, for the classification of the newreptile specimen, three hypotheses can be put forward,with decreasing likelihood: it is a new genus of thalatto-saur, it is a phytosaur or it is a totally new organism. Inany case, this new find will through new light on rhelife environment of the Zorzino fauna: before this, novery large reptile had been found. This fact was explai-ned with the presence of geographical and ecologicalbarriers for both marine and terrestrial organisms,which favoured the rising of an endemic reptilian faunamade of mainly small species. Now we must reconsiderthat, or suppose that those infraplatform basins were sorich in iife that aiso large organisms could develop andbe sustained.Acknouledgements,Thank are ciue to the Soprintendenza Archeologica dellaLombardia which gave us the special permission ro recover thespecimen. The picture is by G.Chiodi. The hand-barrow shafts weremade of the mast of AT brother-in-law old wind-surf: to Carlo oursìncere thanks.RE,FERENCESBasso D. & Tintori A.(1994) - New Triassic isopod crusta-ceans from Northern Italy. Palaeontology v. j7, n. 4, pp801-810, London.Beltan L. & Tintori A.(1980) - The Genus Sauricbtlrys (pisces,Actinopterygii) during the Gondwana period. proc. fifthInt. Gondvtana Syrnp., pp. 53-59, Rotterdam.Jadoul F. Masetti D. Cirilli S. Berra F. Claps M. & S. Frisia\1994) - Norian Rhaetian srratigraphy and paleogeo-graphic evolution of the lombardy basin (BergamascA1p$. 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AN EXCEPTIONAL REPTILE FIND IN THE NORIAN (LATE TRIASSIC) LAGERSTÄTTEN OF ENDENNA (ZOGNO, BERGAMO, ITALY)

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