The Calcari Grigi di Group is a geological group in Italy, dating to roughly between 200 and 190 million years ago and covering the Hettangian to Pliensbachian stages of the Jurassic System. Fossil prosauropod tracks have been reported in the formation.Weishampel, et al. (2004). "Dinosaur distribution." pp. 517–607. It represented a carbonate platform, being located over the Trento Platform and surrounded by the Tofino Formation (deep-water), Massone Oolite (marginal calcarenitic bodies), the Fanes Piccola Encrinite (condensed deposits and emerged lands), the Lombadian Basin Medolo Group and Belluno Basin Soverzene Formation (open marine), and finally towards the south, deep water deposits of the Adriatic Basin. This formation was deposited within a tropical lagoon environment, similar to modern Bahamas which was protected by oolitic shoals and bars from the open deep sea located to the east (Belluno Basin) and towards the west (Lombardia Basin).
The sedimentary cover of the Southern Alps has been recognized as a well-preserved section of the Mesozoic Tethys' southern continental margin, featuring a horst and graben structure linked to the rifting associated with the opening of the central North Atlantic that in the Late Triassic and Early Jurassic, created elevated blocks separated by troughs. While the western margin (Piedmont and Lombardy) quickly submerged in the Early Jurassic (As seen by the Moltrasio Formation), the eastern regions maintained shallow water sedimentation, including the Friuli and Trento Platforms, this last one latter evolving into a pelagic plateau, and separated from the Lombardian basin by the Garda escarpment fault system.
Subunits
Monte Zugna Formation (Hettangian–upper Sinemurian) This formation consists of shallow-water carbonate deposits, several hundred metres thick, organised in metre-scale shallowing-upward cycles. It includes three main informal units: a lower cyclic subtidal unit (bioturbated micritic to bioclastic limestones with green clay interbeds), a middle peritidal unit (alternating stromatolitic bindstones, peloidal mudstones, bioclastic wackestones, and reddish mudstones with mud cracks, teepees, and pedogenic features), and an upper subtidal unit (nodular mudstone-wackestones with increasing grainy intercalations). It was deposited on a broad peritidal to shallow subtidal platform in a warm, tropical shallow sea. The middle peritidal unit records tidal-flat conditions with microbial mats, periodic subaerial exposure, dinosaur tracks and freshwater influence (evidenced by stable isotopes and karst-like features). This surfaces are of less extent than the Latest Triassic local counterparts, maybe as result of size change of the exposed landmasses. Overall arid to semi-arid climate with occasional humid pulses.
Loppio Oolitic Limestone (upper Sinemurian) A prominent, poorly bedded to massive oolitic grainstone unit, up to tens of metres thick, composed mainly of ooids with minor intraclasts and bioclasts, cemented by sparry calcite. It shows progradational geometry and transitions upward from the Monte Zugna Formation. High-energy shallow subtidal shoals and ooid bars on the carbonate platform during a phase of increased carbonate production and relative sea-level stability/highstand. It represents a shift to more open-marine, agitated conditions compared to the underlying peritidal facies. Syn-sedimentary faulting affected this rigid, early-cemented unit, creating extensional structures later sealed by overlying deposits. Locally the so called "Arnioceras time Event", and to a larger extent the Sinemurian-Pliensbachian Event, analogue to the Carnian pluvial episode is seen.
Rotzo Formation (Pliensbachian)
Biota The richest assamblage of the group is the Rotzo Formation.
Foraminifera Genus/FamilySpeciesProvenanceMaterialNotesImagesAeolisaccusA. dunningtoniMonte Cumieli Isolated Tests/ShellsA foraminifer of the Earlandiidae familyEverticyclamminaE. praevirgulianaFoza section; Monte Cumieli Isolated Tests/ShellsA foraminifer of the Everticyclamminidae family.MeandrovolutaM. asiagoensisMonte CumieliIsolated Tests/ShellsA foraminifer of the Cornuspiridae familyMayncinaM. (Paleomayncina) termieriChizzola section; Foza section; Monte Cumieli Isolated Tests/ShellsA foraminifer of the Mayncinidae familyRectocyclamminaR. spp.Monte CumieliIsolated Tests/ShellsA foraminifer of the Everticyclamminidae family.SiphovalvulinaS. spp.Monte CumieliIsolated Tests/ShellsShallow-subtidal benthic foraminifera of Siphovalvulinidae
Invertebrates Indeterminate Ostracod, Gastropod and Echinoderm material is known in the Lavini di Marco ichnosite. Genus/FamilySpeciesProvenanceMaterialNotesImagesAulichnitescf. A. isp.Lavini di MarcoLocomotion/feeding tracesGastropod traces, Present on subtidal beds.GervilliopernaG. buchiChizzola section; Foza section; Lavini di Marco; Monte CumieliShellsPlicatostylidae oysterFavreinaF. sp.Foza sectionCoprolitesDecapod coprolitesPisirhynchiaP. uhligiLavini di MarcoShellsNorellidae brachiopodRhizocoralliumcf. R. isp.Lavini di MarcoBurrows / tracesPart of a moderately diversified assemblage."Terebratula"''T.'' ''dubiosa''Lavini di MarcoShellsTerebratulida brachiopodThalassinoidesT. isp.Lavini di MarcoBurrowsDecapod? convex structures at the base of subtidal beds; also in inter-supratidal interval.ZoophycosZ. isp.Lavini di MarcoTracesPresent in the inter-supratidal bed-set.
Non-Dinosaur Genus/FamilySpeciesProvenanceMaterialNotesImagesBrasilichnium?B.? isp.Lavini di MarcoFootprintsSynapsid track reported at the siteCrocodylomorpha indet.IndeterminateLavini di MarcoFootprintsSmall terrestrial taxonLepidosauria indet.IndeterminateLavini di MarcoFootprints"Lizard-like" trackmaker
Dinosaurs Genus/FamilySpeciesProvenanceMaterialNotesImagesAnchisauripus A. ispp.Lavini di MarcoFootprintsSmall theropod tracksAnomoepus A. isp.Lavini di MarcoFootprintsPrimitive ornithischian tracks; some indicate sitting posture.Ceratosauria? indet.IndeterminateLavini di MarcoFootprintsReferred to the coeval genus Saltriovenator.Eubrontes E. ispp.Lavini di Marco; Chizzola; Pizzo di Levico; Monte Pasubio, Becco di FiladonnaFootprintsMedium to large-sized theropod tracks; common in Upper Subtidal Unit.Grallator G. ispp.Lavini di Marco; Monte Pelmo; other Monte Zugna sitesFootprintsSmall tridactyl theropod tracks.Kayentapus K. hopii K. soltykovensis K. minor K. isp.Lavini di Marco; Chizzola; Pizzo di Levico; Monte PelmoFootprintsMost abundant theropod ichnotaxon in Middle Peritidal Unit; Dilophosaur-like trackmakers.Lavinipes L. cheminiiLavini di MarcoFootprintsBasal Gongxianosaurus-like sauropod.Ornithischia indet. (Iguanodontidae-like)IndeterminateLavini di Marco; other Monte Zugna sitesFootprintsVery deep tridactyl bipedal footprints similar to later iguanodontids; possibly large graviportal forms.Parabrontopodus/Breviparopus-likeIndeterminateLavini di Marco; Becco di Filadonna; Monte PasubioFootprintsNarrow-gauge quadrupedal sauropodomorph tracks; pear-shaped pes, kidney/horseshoe-shaped manus. Larger forms in Upper Subtidal Unit.Sauropodomorpha indet.IndeterminateLavini di Marco; Monte Pasubio (Dente Italiano/Cima Palon); Becco di Filadonna; Monte Finonchio; Malga Buse BisorteFootprintsMedium to large sauropodomorphs; sub-circular underprints with raised rims at Monte Pasubio.Theropoda indet.Indeterminate (Panguraptor-like and Sinosaurus-like pes)Lavini di Marco; Sega di Ala; Monte Pelmo; ChizzolaFootprintsMost abundant dinosaur group across megasites.
Flora Genus/FamilySpeciesProvenanceMaterialNotesImagesAratrisporites A. minorChizzola sectionSporesAffinities with Isoetaceae.Cayeuxia C. spp.Monte Cumieli ImprintsMaybe Bryopsidales.Cerebropollenites C. thiergartiiChizzola sectionPollenAff. Sciadopityaceae coniferChasmatosporites C. spChizzola sectionPollenAffinities with the family Zamiaceae.Classopollis C. spp.Lavini di MarcoPollenCheirolepidiaceae Conifer, dominant palynomorphEodasycladus E. spp.Foza sectionImprintsA green alga of the family Dasycladaceae. Eucommiidites E. troedssoniChizzola sectionPollenType pollen of the Erdtmanithecales, related to the Gnetales.Fanesella F. dolomiticaFoza sectionImprintsA green alga of the family Dasycladaceae.Linoporella L. spp.Foza sectionImprintsA green alga of the family Dasycladaceae.Palaeodasycladus P. mediterraneus P. gracilis P. spp.Foza section; Lavini di Marco; Monte CumieliImprintsA green alga of the family Dasycladaceae. A reefal algae usually found in carbonate settings along all the MediterraneanPorcellispora P. longdonensisLavini di MarcoSporesAffinities with Bryophyta or Marchantiophyta, potentially Riellaceae.Retitriletes R. clavatoidesChizzola sectionSporesAff. Lycopodiaceae Sestrosphaera S. liasinaMonte CumieliImprintsA green alga of the family Triploporellaceae.Terquemella T. spp.Foza sectionImprintsA green alga of the family Dasycladaceae. Tersella T. genotii T. alpinaMonte CumieliImprintsA green alga of the family Dasycladaceae. Thaumatoporella T. parvovesiculifera T. spp.Lavini di Marco; Monte CumieliImprintsA green alga of the Thaumatoporellales group. The dominant alga locally
See also
List of dinosaur-bearing rock formations Rotzo Formation List of stratigraphic units with sauropodomorph tracks Prosauropod tracks
Footnotes
References Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. .