GAIA N'15, LlSBOAlLISBON, DEZEMBRO/DECEMBER 1998, pp. 355-367 (!SSN: 0871-5424)
THEROPOD FOOTPRINTS IN THE CRETACEOUS ADRIATIC-DINARIC CARBONATE PLATFORM (ITALY AND CROATIA)
Fabio M. DALLA VECCHIA MuseD Paleontologico Cittadino di Monfalcone. Via Valentin is 134, t~34074 MONFALCONE. ITALY
ABSTRACT: Theropod footprints are known in ten sites of late Hauterivian/early Barremian (1), late Barremian (1), late Albian (5) and late Cenomanian (3) age on the Adriatic-Dinaric carbonate platform (Italy and Croatia). Most of the footprints belongs to small- to medium size individuals; large ones are known in the upper Hauterivian-upper Barremian sites and are much rarer in upper Albian ones. Small- to medium-size theropods are associated with small sauropods in the late Albian and perhaps in late Cenomanian. Most of the footprint bearing beds are marine carbonates exposed to subaereal desiccation in tidal or lagoon set tings. Data suggest that theropods were just passing through these environments. The Adriatic-Dinaric carbonate platform is a special case of an intraoceanic, or at best very far away from any continental area, carbonate platform with a local dinosaur fauna.
INTRODUCTION the main paleoichnological works (HAUBOLD, 1971; LOCKLEY, 1991; THULBORN, 1990) and in several The Adriatic-Dinaric carbonate platform is a fos papers dealing with local ichnoassociations (e.g. si l carbonate platform of Jurassic-Cretaceous age. LEONARDI, 1984; PITTMAN, 1989). It was involved in Alpine-Dinaric orogeny and at present it crops out mainly in NE Italy (Pre-Alps, Following these features most of the tridactyl, Karst), SW Slovenia (Karst, Istria), W Croatia (Istria, mesaxonic footprints, often organized in bipedal Dinarids), W Bosnia and Montenegro (Dinarids). tracks found in the Cretaceous limestones of Adriatic-Dinaric carbonate platform are here consid Sites with dinosaur fossils are found in Creta ered to be theropod footprints. ceous limestones exposed along the western coast of the Istrian peninsula (Croatia), in Istrian islands, in Footprints in a track rarely have the same size: I the Italian Karst (Trieste) and in a block quarried in report for each trackway just one value of L which the Cansiglio Plateau (NE Italy) (for references see corresponds to the media of the lengths or the length DALLA VECCHIA, 1997 and DALLA VECCHIA & TAR of the best preserved print. I consider small-size LAO, 1995). Footprints probably made by theropods theropods those with L<15 cm, middle-size those are present in most of these sites (Fig. 1). with 15
355 artigos/papers F.M. DALLA VECCHIA
Dinaric carbonate platform was completely separated from continental areas, dominated by sili coclastic fluvial-lacustrine sedimentation. However, the affinity with the associations of foraminifers of
1...,...... Northern Africa, suggests a strict connection with
1 UDINE // the African-Arabian continent during Hauterivian • C.! Barremian (CHERCHI & SCHROEDER, 1973). There is a general agreement that it was separated from the C Arabian-African plate by the opening of the Eastern " "'-ryIESTE Mediterranean Ocean during Early Aptian.
DATA
UPPER HAUTERIVIAN/LOWER BARREMIAN
Sarone, Cansiglio Plateau, Pordenone provin ce, NE Italy. A limestone block with a large (L=36 cm) thero pod footprint preserved as positive hiporelief, was discovered in the pier of Ravenna (Fig. 1(1), 2A, 3A). Also a sauropod manual print is preserved along with the theropod footprint (DALLA VECCHI A, in
o km 25 50 press). The block comes from a quarry open in the Cretaceous limestones of the southern flank of the Cansiglio Plateau, northern point olthe Adriatic plat Fig. 1 - Location of the sites. 1 - Sarone, Cansiglio Pla form (DALLA VECCHIA & VENTURINI, 1995). The infill teau, upper Hauterivian/lower Barremian. 2 - Pogleda ing is a wackestone with foraminifers and ostracods lo/Salsa promontory, Main Brijuni/Brioni island, upper Bar while the stratigraphical section from which the remian. 3 - Puntizela/Puntesella, upper Albian. 4 - Plo~e block comes is composed mainly of mUdstones with Promontory, Main Brijuni/Brioni island, upper Albian. ostracods and desiccation structures, and pedoge 5 - Kamnik (Plijesivac) Promontory, Main Brijuni/Brioni is netic breccias, sometimes with black pebbles. land, upper Albian. 6 - Mirna/Quieto river mouth, upper Albian. 7 - Cervar/Cervera, upper Albian. 8 - Fenoliga islet, Kolone, BaleNal/e, SW Istria, Croatia. upper Cenomanian. 9 - Grakalovac Promontory, upperCe nomanian. 10 - Lovre~ica/S. Lorenzo di Daila, upper Ceno This locality preserves dinosaur bone remains in manian. carbonate lacustrine sediments (DINI , TUNIS & VEN TURINI , 1998; TUNIS, SPARICA & VENTURINI, 1994). It is a rich outcrop which unfortunately lies below the considered to be mainly a region of marine sedimen present sea level. For this reason only a limited tation therefore a shallow marine environment even number of specimens, (about 200) mostly fragmen if repeated emersions, sometimes long-lasting, tary, were COllected. Most of the identifiable bones were locally identified (see for example MATI(~EC et belong to small to large-size titanosauriform, diplo al., 1996; TUNIS, SPARICA & VENTURINI, 1994; VELIe, docimorph and, perhaps, camarasaurid sauropods Til3LJAR & SOKAC , 1989). (DALLA VECCHIA, 1994, 1998). Only recently a tooth and an ungual phalanx belonging to small theropods It was situated on a microplate (Apulian micro were discovered. The tooth isashed crown 12.5 mm plate or African Promontory; CHANNEL, D'ARGENIO long, resembling those of the velociraptorine dro & HORVATH, 1979) placed between African-Arabian meosaurids (see CURRIE, RIGBY & SLOAN , 1990), and Laurasian plates. Following DERCOURT, RICOU because it is laterally compressed, elongate and re & VRIELYNCK (1993) the Adriatic-Dinaric carbonate curved, and denticles of the distal carina are decid platform was placed at the north-western end of a edly larger than the mesial ones. In fact, in the upper larger, narrow and E to Welongated, shallow marine part of the tooth there are six denticles per mm on paleogeographic unit. This unit, made only of car the distal carina and eight denticles per mm on the bonate platforms, included from W to E the Gavrovo mesial carina ("denticle size difference index" of zone (Bulgaria), Tripolitza, Menderes, Seydisehir, RAUHUT & WERNER (1995) is therefore 1.33). How Eastern Taurus and Muzurdan (Turkey) and was ever, the preserved denticles do not point apically surrounded by deep marine troughs. Therefore, fol like those of the teeth of velociraptorine dromeo lowing the paleogeographic maps of DERCOURT, RI saurids. The very small (8.75 mm long) ungual pha- COU & VRIELYNCK (1993) the Cretaceous Adriatic-
356 THEROPOD FOOTPRINTS IN THE CRETACEOUS ADRIATIC-DINARIC CARBONATE PLA TFORM
Fig. 2 - Theropod footprints. A - Sarone, Cansiglio Plateau (NE Italy), upper Hauterivian-lower Barremian. B - Po gledalo/Salsa Promontory, Main Brijuni/Brioni island (SW Istria), upper Barremian. C - Puntizela/Punteselia (SW Istria), upper Albian. D - Plote II , Main Brijuni/Brioni island (SW Istria), upper Albian, cast. All scale bars in centimetres. (Contin ued).
357 F.M. DALLA VECCHIA
Fig. 2 (continued) - Theropod footprints. E - Kamnik II , Main Brijuni/Brioni island (SW Istria), upper Albian, cast. F - C:ervar/Cervera I (Central-W Istria), upper Albian, cast. G - C:ervar/Cervera II (Central-W Istria), upper Albian. H - Mirna/Quieto river mouth (central-W Istria) upper Albian. All scale bars in centimetres. (Continued).
358 THEROPOD FOOTPRINTS IN THE CRETACEOUS ADRIATIC-DINARIC CARBONATE PLA TFORM
Fig . 2 (continued) - Theropod footprints. 1- Fenoliga Islet (S Istria), upper Cenomanian, cast. J - Grakalovac (SW Is tria), upper Cenomanian, cast. K - Lovre~ica/S. Lorenzo di Daila (N Istria), upper Cenomanian. L- Lovre~ica/S. Lorenzo di Daila (N Istria), upper Cenomanian, cast. All scale bars in centimetres.
359 F.M. DALLA VECCHIA '
lanx is narrow, low, elongate and pointed, not very Plo(;e Promontory ("Rocca Kapp" of BACHOFEN much recurved; the ventral margin of the proximal ECHT, 1925), Main BrijunilBrioni Island, SW Is ungual blade is flat whereas that of the distal ungual tria. blade is blunt; the groove crosses diagonally the In this site there are two printed surfaces (I , lower, phalanx ending dorsally well before its point. The arid II, opper) at the top of two superimposed layers proximal part is not deep, the articular facet does not (Fig. 1 (4), 20,30). The site was described by the exceed the ungual blade in height and the articular paleoichnological point of view by BACHOFEN-ECHT surface occupies most of the articular facet. The (1925) who wrongly attributed the footprints to specimen shows some resemblance with the or Iguanodon MANTELL. After the description by the nithomimid manual phalanges because of its overall German paleontologist some footprints were taken morphology and the presence of a relatively small away. For example, none of the large tridactyl foot flexor tubercle displaced somewhat distally (see prints reported by him is now present in the outcrop. OSM6LSKA & BARSBOLD, 1990; RAUHUT & WERNER, Five slabs with a footprint each are stored in a hou ~e 1995) but belongs to a chicken-size individual. of the port of the island which was once a museum. There is a groove between the main body olthe pha They testify the presence of relatively large thero lanx and the flexor tubercle, which could indicate an pods (L -40 cm and -32 cm) but give no other infor uncomplete fusion of the two and suggests that the mation. individual was immature, as also indicated by small size. These specimens, at present under the care of The narrow surface of level I presents two tracks the municipality of BaleNalle, are the only theropod and a couple, for a total of 12 footprints; L=13.5 cm , bones recorded up to now from the Istrian region. 21 cm and 21.5 cm. In the level II there are 12 tracks, two couples and UPPER BARREMIAN five single isolated footprints, for a total of about 60 preserved footprints; L=14-26 cm. Larger footprints Pog/eda/olSalsa Promontory, Main BrijunilBrio (two tracks?) are considered to came from this hori ni Island, SW Istria. zon . In this site there are only large tridactyl footprints The footprint-bearing level I is a wackestone with on a single bed surface exposed on the shore as an foraminifers, small gastropods and desiccation elongated band (Fig. 1(2), 2B, 3B). The state ofpres structures. Level II is a packstone-grainstone with ervation is not good. Five short tracks, seven cou foraminifers and gastropods; the printed surface ples and 19 single isolated prints, for a total of about shows mud cracks. High energy accumulations of 60 footprints are recognizable. L=24-45 cm; size gastropod shells and ripple marks are present in the distribution is shown in Figure 5. The substrate was stratigraphic section (Fig. 4). a "fenestral micrite" overlain by stromatolites and "pellettallimestones" with ripple marks indicating an KamniklPljiesivac Promontory, Main BrijunilBri intertidal environment (VELIC & TISLJAR, 1987; Fig. oni Island, SW Istria. 4). In this outcrop (Fig. 1 (5)) there are two track UPPER ALBIAN bearing surfaces at the top of superimposed beds but only the upper one presents footprints ascrib Puntize/alPuntesella, FazanalFasana; SW Is able to theropods (Fig. 2E, 3E-F) while the lower one tria. has just a medium-size ornithopod trackway. This site presents two footprint-bearing surfaces There are four theropod tracks, with badly pre placed at different stratigraphic levels (Fig. 1(3)). served footprints, for a total of about 70 footprints. Level II is placed few metres above level I. L=15.5-17.5 cm. Level II has a track with five poorly preserved The footprint-bearing level is a mudstone foorprints (in the best preserved L=17.5 cm). The wackestone with foraminifers and ostracods. The printed bed is a pellettal mudstone-wackstone with layer below presents ripple marks (Fig. 4). rare ostracods; the stratigraphic section presents high energy bands of grainstone with gastropod Cerveral(';ervar, Camping Solaris, Punta del shells. Dente, NW Istria. Level I preserves a segment of a track with four In this site there are two separated footprint footprints but only three preserved (in the best one bearing surfaces which could be different horizons L=20 cm ; Fig . 2C, 3C). The printed bed is a (DALLA VECCHIA, 1994, 1996; DALLA VECCHIA & mUdstone-wackestone with rare ostracods and fo TARLAO, 1995) (Fig. 1(7), 2F-G, 3G-H). One is ex raminifers; mud cracks are presenton the surface. posed along the shore (level I), the other (level II),
360 THEROPOD FOOTPRINTS IN THE CRETACEOUS ADRIA TIC-DINARIC CARBONATE PLA TFORM
IV
A 5 em 8 c
)- IV ~~y E G H
J K L M N
Fig. 3 - Drawings of some theropod footprints from the Cretaceous Adriatic-Dinaric Carbonate Platform. A - Sarone, Cansiglio Plateau (NE Italy), upper Hauterivian-lower Barremian (see Fig . 2A). B - Pogledalo/Salsa Promontory, Main Bri juni/Brioni island (SW Istria), upper Barremian, taken from the cast (see Fig. 2B). C - Puntizela/Puntesella (SW Istri a), up per Albian, (see Fig. 2C). D - Plote II , Main BrijunilBrioni island (SW Istria), upper Albian, taken from the cast (see Fig. 2D). E - Kamnik II , Main Brijuni/Brioni island (SW Istria), upper Albian, taken from the cast (see Fig. 2E). F - Kamnik II , Main Bri junilBrioni island (SW Istria), upper Albian, taken from the cast. G - (;ervar/Cervera I (Central-W Istria), upper Albian, taken from the cast (see Fig . 2F). H - Cervar/Cervera II (Central-W Istria), upper Albian, taken from the cast (see Fig. 2G). 1- Mirna/Quieto river mouth (eentral-W Istria) upper Albian, (see Fig. 2H). J - Fenoli ga Islet (S Istria), upper Cenomanian, taken from the cast (see Fig.21). K - Grakalovae (SW Istria), upper Cenomanian, taken from the cast (see Fig.2J). L - Grakalovae (SW Istria), upper Cenomanian, taken from the cast. M - Lovretiea/S. Lorenzo di Daila (N Istria), upperCe nomanian, taken from the cast (see Fig. 2K). N - Lovretiea/S. Lorenzo di Daila (N Istria), upper Cenomanian, taken from the cast (see Fig. 2L). Drawn to scale; scale bar = 5 em .
361 F.M. DALLA VECCHIA
~ ~ much wider (33x13 m), is placed few tens of meters .. .. ~ 00 ~z inland, and is the bed of an abandoned large quarry. ~~ "'0 ~ 0:0: ~o .. ~ w 0 In the level I there are 12 tracks, five couples of ~ >- ~"" .. r '" Z r ~ '" footprints and 14 single isolated footprints, for a total O.,.';I~I - " .. ;.t" ..... "1 of about 60 footprints. L=16.5-24 cm. Probably there I II ID IV V are also footprints of small-size sauropods. The footprint-bearing level is a pelletal wackestone with ostracods, foraminifers and desiccation structures; in the stratigraphic sequence there are some levels I cP: . ~ [~ with large mud-cracks. In level II there are many tracks and ten s of single isolated footprints. The study of this material is just KAMNIK•• beginning. L range seems to be approximately the same of level I. Many small-sized sauropod foot $ I [ prints are present too (DALLA VECCHIA, 1994, 1996). z 362 THEROPOD FOOTPRINTS IN THE CRETACEOUS ADRIA TIC-DINARIC CARBONATE PLA TFORM Grakalovac Promontory, Premantural Promonto 11 re, S Istria. 10 The printed surface is exposed along the shore in 9 8 N~27 the upper part of a cliff as a narrow and few metres 7 M~32.25 long band (Fig. 1(9), 2J, 3K-L). Three tracks and a 6 single footprint are preserved for a total of 13 foot 5 prints. L=15-25 cm. The printed layer is a biotur 4 bated wackestone-packstone with foraminifers, in a 3 stratigraphical sequence with rudist limestone beds 2 and mounds. Lovrei':ica/S. Lorenzo di Daila, UmaglUmago, Fig . 5 - Size distribution of late Barremian footprints. NW Istria. In this site there is a single footprint-bearing sur face exposed along the shore as a 20 m long band bearing beds are deposited in marine environments (Fig. 1 (1 0), 2K-L, 3M-N). The state of preservation of as tidal flats or lagoons but most of them presents the specimens is not good. There are five tracks, evidence of subaerial exposure as mud cracks (e.g. seven probable tracks, three couples and foursingle Puntizela/Puntesella I, Ploce II and Gervar/Cervera isolated footprints, for a total of 58 footprints. II) or desiccation microstructures (e.g. Pogledalo, L=14.5-25.5 cm. The printed bed is a microbreccia Ploce I, Fenoliga). with abundant matrix with foraminifers and clasts with desiccation structures; it is intercalated among Only a population of large theropods is testified, rudist limestone beds. It is probably a storm layer. in the single site of late Barremian age. Most of the footprint lengths are included in the interval 30-38 Size distribution of the late Cenomanian thero cm (Fig. 5) corresponding to h values ranging 120- pod footprints is reported in Figure 7. 155 cm to 152-190 cm, with a separate group of smaller footprints and some larger; M=32.25 cm. INTERPRETATIONS There is not a clear mean, having three small peaks Even if at present the study of the Istrian foot for 30 cm, 35 cm and 38 cm. prints is far from concluded, some observations can Different is the situation in the upper Albian, be anticipated here. where we have a larger sample. Large theropods Exposures suited to find vertebrate fossil foot are rather uncommon and middle-size individuals prints are limited to just a narrow band exposed are prevailing (Fig. 6). In fact, most of the footprint along the coast in Istria, to quarry beds orto quarried lengths are included in the interval 16-24 cm corre blocks (the case of the footprints from Cansiglio Pla sponding to h values ranging 64-72 cm to 96-115 cm. teau). Despite this limited sampling area we found The mean is21 cm (h = 84-98 cm), M = 20.75 cm and significant evidence of dinosaurs in the northern part the distribution is skewed toward smaller forms. of the Adriatic-Dinaric platform, which has been less The late Cenomanian assemblage is composed disturbed tectonically. This is probably just a small only by middle-size individuals (Fig. 7); the mean is portion of the real dinosaur record of this region. At 21 cm, M = 19.55 cm and the distribution is skewed least during some intervals of the Cretaceous Peri toward smaller forms. There are not significative od, the platform was inhabited by populations of di size differences with the late Albian assemblage, if nosaurs. The emersions which permitted the we exclude the total absence of large individuals. presence of the dinosaurs are most probably related Anyway, we must keep in mind that the sample is to tectonic events rather than eustatic sea level fluc much smaller. tuations even if the influence of the latters could have played a role. In fact the Apulian Promontory or At a first preliminary survey there are some differ Microplate during the Cretaceous times was begin ent theropod ichnotaxa in the Cretaceous of Istria. ning to collide with "Europe". Besides, late Albian This means that a certain degree of taxonomical di and late Cenomanian are intervals of worldwide sea versity is suggested not only by different sizes but level high stand (DERCOURT, Rlcou & VRIELYNCK , also by footprint morphology (see Fig. 2-3). Its worth 1993). to note that the one here reported is the only thero pod evidence in that part of the Cretaceous world. All the sites with footprints are in prevailing ma No skeletal record of such theropod populations re rine carbonate sequences but with sedimentological mains, except the tooth and the phalanx of late evidence of emersion (pedogenetic breccias, karsti Hauterivian-early Barremian age. fication of carbonates, bauxites, marsh-lacustrine deposits, etc.), mainly during late Albian. Footprint- 363 F.M. DALLA VECCHIA If the carbonate platform was connected with the 8 African-Arabian continent (at least in pre-Aptian N:.27 times), the most probable source area for coloniza 7 ..;.. tion was Africa via Middle East. No osteological rec 6 M=19.55 ord of theropods is known in the Middle East if we 5 - exclude scanty remains in the ?Cenomanian of Syria (WEISHAMPEL, 1990). Even if some fragmen 4 tary remains have been reported during last 80 3 years (e.g. DALLA VECCHIA, 1995; DEPERET & SA 2 r- '- VORNIN, 1925; LAPPARENT, 1960; RAUHUT & WER - NER, 1995; RUSSELL, 1996; STROMER, 1915, 1931, 1 r 1934), African theropods of Aptian to Cenomanian 11 12 1314 15 16 17 18 19 20 21 22 23 24 25 26 age are just beginning to be known in detail (SERENO et al., 1994, 1996). As the general rule with terres Fig. 7 - Size distribution of late Cenomanian foof: trial vertebrates (BEHERENSMEYER, WESTERN & prints. DECHANT-BOAZ, 1979) the remains of large thero pods are much more represented in the sample than those of small to medium-size ones. This point out less bird Emu (Dromaius novaehollandiae that the osteological record (biased by strong tapho (LATHAM», which has tridactyl feet and h compara nomical control) testifies justa little part of the real di ble to that of most ofthe Cretaceous theropods of Is nosaur diversity. On the other side, ichnological tria, covers great distances at a costant speed of record is not suitable for phylogenetical analyses 7km.h-' (FOLCH, 1992). Of course, this observation but opens windows on real distribution and possible is not enough to say that medium-size Cretaceous local and general diversity of taxa. theropods had a similar behaviour and, conse quently, the same metabolism of the bird Emu. If the platform was intraoceanic, separate from continental regions by deep seaways since Early Ju In outcrops with many footprints and tracks there rassic, as DERCOURT, RICOU & VRIELYNCK (1993) is a roughly bimodal distribution of directions. Main suggest, the colonization from a source area is ap directions are more or less perpendicular (e.g. Kam parently impossible. nik II, Plo~e II, Lovre~ica / S.Lorenzo) ; sometimes it is apparently roughly unimodal (Grakalovac). Such None of the theropods was running; the most preferential directions have been often interpreted common gait was a relatively fast walking (Kamnik, as evidence of social behaviour. I think that in the Plo~e II, Puntizela/Puntesella, Cervar/Cervera I, cases under examination another explanation is Fenoliga, Grakalovac, Lovre~ica/S.Lorenzo). As a possible. The bimodal distribution with more or less general feature, they were going straight or in a perpendicular directions reflects the typical behav slightly undulating way, without big changes ofdirec iour of vertebrates reaching the shore: a direction tion, stops, or the irregular walking of an animal more or less normal to the local coastline (the short searching for food. The estimated V values are as a est way to reach it) and a second one parallell to (a rule higher than AWS, in many cases nearly two free way with the lateral bondary of the water). The times higher (e.g., Cervar/Cervera I and Lovre movement was in both the two verses of each main ~ica/S.Lorenzo) . This suggests that the animals direction. The same pattern is present in theropod were just passing through the environments were trackways in coastal settings of late Albian-early Ce they left the prints with something like a cruising nomanian age of Israel and AVNIMELECH (1966) speed. It is interesting to note that the modern fiight- came to similar conclusions about the behaviour of the trackmakers. 11 Dinosaur body and trace fossils are known in the 10 carbonate platforms which surrounded the Gulf of 9 Mexico during Aptian-Cenomanian times, mainly in B 7 the lower-middle Albian but also in the Cenomanian 6 N'53 (PITTMAN, 1989). However, the paleogeographic 5 M '20.75 setting was different from that of the Adriatic-Dinaric 4 platform. The Gulf of Mexico platforms bordered the 3 southern part of the North American continent, and 2 1 the depositional environment for most of the dino saurfossils has been identified as the shoreline tran sition between continental clastic sediments and the Fig. 6 - Size distribution of late Albian footprints. carbonate tidal flats (PITTMAN, 1989). 364 THEROPOD FOOTPRINTS IN THE CRETACEOUS ADRIA TIC-DINARIC CARBONA TE PLA TFORM Paleoichnological associations are similar, hav In the only site of late Barremian age just large ing in both cases a dominance of supposed thero theropods are recorded . pods , a significative but lesser presence of Most of the theropod evidence has a late Albian sauropods and rarer ornithopods. This is in agree age, with five sites with at least nine printed levels. ment with the concept of Brontopodus ichnofacies There was the prevalence of medium-size individu (LOCKLEY, HUNT & MEYER, 1994). als, while large ones are testified just in one outcrop The predominance of carnivorous dinosaurs is (Plote). In one site medium-size theropod footprints not so meaningful from the palaeocological point of are associated to small sauropod footprints. view if you accept my hypothesis that the animals Upper Cenomanian sites present only medium where just passing through: they were not in their size theropods. In just one site they are associated normal habitat. It is clear for some Cenomanian sites with a possible sauropod track. where footprints are preserved in a sequence with prevailing rudist rudstones and mounds. Tidal flats, The Adriatic-Dinaric carbonate platform is a spe shores and similar environments are rather uncom cial case of an intraoceanic carbonate platform, or at fortable habitats for large terrestrial vertebrates; I do best very far away from continental land, with a local not know large and extant terrestrial vertebrates dinosaur fauna. The paleogeographic and evolu which use to spend most of their time in such envi tionary significance of the Istrian dinosaur remains ronments. I suspect that dinosaurs lived usually few is just beginning to be investigated. hundred of metres or few kilometres inland, where there was vegetation and fresh water but no or ACKNOWLEDGEMENTS scarce sedimentation. Tidal fiats, shores and similar I thank A. Tarlao, M. Tentor and G. Tunis for the muddy and wet environments were just routes and help on the field and the sedimentological the only place where large tetrapods could leave evi stratigraphical sampling, and the staff of the Gruppo dence of their presence. I do not suggest that the di Speleologico A.D.F. - Museo Paleontologico Cit nosaurs were migrating along these routes: this is a tadino of Monfalcone for the technical , logistical and possibility but cannot be demonstrated. economical support. The research of A. Tarlao, who Some faunal differences are evident between discovered most of the new sites, has been funda U.S.A. sites and the Istrian ones. The large thero mental. Sandro Venturini did the sedimentological pods are dominant in the Gulf sites (PITTMAN, 1989) description and interpretation of the thin sections. I while medium-size ones are much more common in thank J. G. Pittman for the discussion and advice on Istria. This is particularly true if we compare the paleoichnological ground; J. Moratalla and T.H. roughly coeval Albian associations. The same hap Holtz for the critical review of the manuscript and for pens with sauropods: upper Albian sauropod foot correcting the English grammar. prints of Istria are comparatively ve ry small, The field work was possible thanks to the eco probably the smallest recorded in the world. I sus nomical support of The Dinosaur Society. This work pectthat such "dwarfism" could be related to insular was supported also by MURSTfunds (Dr. G. Tunis). ism, since the isolated geographical position of the carbonate platform. ABBREVIATIONS CONCLUSION AWS - average walking speed; h - heigth at hip; L - footprint length; M - media; N - number of speci Even if the Adriatic-Dinaric carbonate platform mens; SL - stride length; V - absolute speed. was an area of prevailing marine carbonate sedi mentation, isolated or at best very far from continen REFERENCES tal areas dominated by silicoclastic deposition, ALEXANDER, R.MCN. 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