Saltriovenator(meaning "Saltriohunter ") is a genus ofceratosauriandinosaurthat lived during theSinemurianstageof theEarly Jurassicin what is nowItaly.Thetypeand only species isSaltriovenator zanellai;in the past, the species had been known under the informal name "saltriosaur". Although a full skeleton has not yet been discovered,Saltriovenatoris thought to have been a large, bipedal carnivore similar toCeratosaurus.
| Saltriovenator Temporal range:Early Sinemurian
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| Selected elements of the holotype | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | †Ceratosauria |
| Genus: | †Saltriovenator Dal Sassoet al.2018 |
| Species: | †S. zanellai
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| Binomial name | |
| †Saltriovenator zanellai Dal Sassoet al.2018
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Discovery and naming
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On 4 August 1996, the first remains ofSaltriovenatorwere discovered by amateur paleontologist Angelo Zanella, searching forammonitesin theSalnovamarble quarry inSaltrio,northern Italy. Zanella had already been working for theMuseo Civico di Storia Naturale di Milanoand this institution after being informed sent out a team to investigate the find.Cristiano Dal Sassoand the volunteers of the Paleontological Group of Besano, under the direction ofGiorgio Teruzzimanaged to salvage a number of chalk blocks visibly containing bones. The skeleton had shortly before its discovery been blown to pieces by explosives used in the quarry to break the marble layers. Blocks that had been secured were inserted into a bath offormic acidfor 1,800 hours to free the bones.[1]Initially, 119 bone fragments were reported to have been collected in total;[2][3]this was later increased to 132. However, most cannot be exactly identified.[1]
In 2000, the museum opened a special exhibition of the bones. On this occasion, Dal Sasso provisionally gave the dinosaur, now thought to be a species new to science, the Italian nameSaltriosauro.Although this has been occasionally Latinised to "Saltriosaurus", even in the scientific literature, in both the Italian and Latin form it remained an invalidnomen nudum.[1]
In December 2018, Dal Sasso, Simone Maganuco and Andrea Cau named and described the specimen as thetype speciesSaltriovenator zanellai.The generic name combines a reference to Saltrio withLatin,venator,"hunter", a common suffix in the names of theropods. The authors pointed out that avenatoris also a type of Romangladiator.Thespecific namehonours Zanella. Because the article was published in anelectronic publication,Life Science Identifierswere necessary to make the name valid. These are 8C9F3B56-F622-4C39-8E8B-C2E890811E74 for the genus and BDD366A7-6A9D-4A32-9841-F7273D8CA00B for the species.Saltriovenatoris the third dinosaur named from Italy, the first from the Alps and the second theropod from Italy, afterScipionyx.[1]
Theholotype,MSNM V3664,was found in a layer of theSaltrio Formationdating from the earliest earlySinemurian,199 million years old. It consists of a fragmentary skeleton with a lower jaw. About 10% of the skeleton has been discovered, including a tooth, a right splenial, a right prearticular, a neck rib, fragments of the dorsal ribs andscapulae,a well preserved but incompletefurcula,humeri,metacarpalII,phalanxII-1, phalanx III-1, phalanx III-2, manualungualIII, a distaltarsalIII, a distal tarsal IV and theproximalsecond to fifth metatarsals. The holotype individual likely died on the shores of an ancient beach before being washed out to sea. After death, the skeletal remains suffered from prolonged transport, during which many bones were lost and the remaining ones highly fragmented.[citation needed]
AlthoughSaltriovenatorwas not aquatic, the environment in which the carcass was deposited was likelypelagic,judging by the associatedammonites.The locality is also rich incrinoids,gastropods,bivalves,brachiopodsandbryozoans.[4]Deposition occurred on a slope between a shallow carbonate platform and a deeper basin. Various scratches, grooves, and striations indicate that the carcass was subject to scavenging by marine invertebrates. The specimen represents a subadult individual, nearing its maximum size, of which the age has been estimated at twenty-four years.[1]
Description
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Because of the fragmentary nature of the remains, it was impossible to directly measure the size of the animal. The describing authors therefore compared the fossils with those of two theropods of a roughly similar volume. Comparing with the skeletal elements of MOR 693, anAllosaurus fragilisspecimen, they conservatively concluded that theSaltriovenatorholotype individual was at least seven to eight metres long. This would makeSaltriovenatorthe largest known theropod living before theAalenianstage, 25% longer thanCeratosaurusfrom the late Jurassic. Comparing withCeratosaurusitself, resulted in a body length of 730 centimetres, a hip height of 220 centimetres and a skull length of eighty centimetres. The thighbone length would then have been about eighty to eighty-seven centimetres, which indicates a body weight of 1160 to 1524 kilogrammes. Another method consisted in extrapolating from the known length of the forelimb. Applying the usual limb ratio indicated a hindlimb length of 198 centimetres. The thighbone would then have been 822 to 887 millimetres long, indicating a weight of 1269 to 1622 kilogrammes.[1]
Classification
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The precise systematic position ofSaltriovenatorhas been traditionally uncertain, but it is known to be atheropod.[2][3]Dal Sassooriginally referred it to theTetanurae[5]He later considered that it may represent anallosauroid,although in either case it would predate other members of the clades by roughly 20-30 million years.[6]Benson considered it a member ofCoelophysoideain his review ofMagnosaurus.[7][8]The presence of awishbone[6]may support its placement as a tetanuran, although wishbones have been reported from coelophysoids.[9][10]
The 2018 description paper ran a large phylogenetic analysis, and found it to be a basalceratosaur,the sister-taxon ofBerberosaurus.[1] The phylogenetic analysis is as shown:
Provenance and Paleoenvironment
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Saltriovenatorwas found on an open marine environment, where it was probably washed from the nearest mainland, being scavenged by invertebrates as proven by the presence ofSedilichnussp. on the bones.[1]This depositional environment, part of theSaltrio Formationis considered as part of a proximal slope or ramp that was probably an open subtidal zone reached by the effects of storm waves and with constant bottom currents.[1]Since the beginning of the Jurassic, fromHettangianto earliestSinemurianon the westernLombardy Basinthere was a notorious continental area that was found to be wider than previously thought, where a warm humid paleoclimate developed.[11]The Dinosaur Fossils found on the Saltrio formation could have been translated from this area, or alternatively, theArbostora swell(that was located at the north of the Saltrio formation, onSwitzerland).[12]This was an emerged structural high close to theSaltrio Formation,that caused a division between two near subsiding basins located at Mt. Nudo (East) and Mt. Generoso (West).[12]It settled over a carbonate platform linked with other wider areas that appear along the west to the southeast, developing a large shallow water gulf to the north, where the strata deposited was controlled by a horst and tectonic gaben.[12] Several outcrops of the so-called "terra rossa" paleosoils were also found, including atCastello Cabiaglio-Orino,a dozen of kilometers West of Saltrio.[13][14]These outcrops show that the emerged areas that on the Hettangian-Sinemurian, the current location of the modernMaggiore Lakewas covered with forests, what was proven by the presence of large plant fragments on theMoltrasio Formation.[11]The plants have been recovered between the locations ofCellinaandArolo(eastern side of Lake Maggiore), from rocks that have been found to be coeval in age to theSaltrio Formation.[4]The Flora includes genera such asBennettitales(Ptilophyllum), terrestrialAraucariaceae(Pagiophyllum), andCheirolepidiaceae(Brachyphyllum), that developed on inland areas with dry-warm conditions.[4] Saltriovenatorprobably come from this nearby landmass, as other emerged zones, such as the Trento Platform where it's far of the location of discovery. If so, this theropod was probably the largest predator on the region.[1]
See also
editReferences
edit- ^abcdefghijDal Sasso, C; Maganuco, S; Cau, A. (2018)."The oldest ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, sheds light on the evolution of the three-fingered hand of birds".PeerJ.1(1): e5976.doi:10.7717/peerj.5976.PMC6304160.PMID30588396.
- ^abThe Theropod Database
- ^abMatthew T. Carrano, Roger B. J. Benson, Scott D. Sampson:The phylogeny of Tetanurae (Dinosauria: Theropoda).Journal of Systematic Palaeontology. Bd. 10, Nr. 2, 2012
- ^abcLualdi, A. (1999). "New data on the Western part of the M. Nudo Basin (Lower Jurassic, West Lombardy)".Tübingen Geowissenschaftliche Arbeiten, Series A.52(1): 173–176.
- ^Dal Sasso, C. (2001).Dinosauri italiani(2 ed.). Venezia: Marsilio Editori. pp. 45–66.
- ^abDal Sasso, Cristiano (2003)."Dinosaurs of Italy".Comptes Rendus Palevol.2(1): 45–66.doi:10.1016/S1631-0683(03)00007-1.Retrieved28 December2021.
- ^Benson, Roger B. J. (2010)."The osteology ofMagnosaurus nethercombensis(Dinosauria, Theropoda) from the Bajocian (Middle Jurassic) of the United Kingdom and a re-examination of the oldest records of tetanurans ".Journal of Systematic Palaeontology.8(1): 131–146.doi:10.1080/14772011003603515.S2CID140198723.
- ^Rauhut, Oliver W. M. (2003).The interrelationships and evolution of basal theropod dinosaurs (= Special Papers in Palaeontology. Bd. 69)(PDF)(1 ed.). London: The Palaeontological Association. pp. 1–213.Retrieved28 December2021.
- ^Rinehart, Larry F.; Lucas, Spencer G.; Hunt, Adrian P. (2007)."Furculae in the Late Triassic theropod dinosaur Coelophysis bauri"(PDF).Paläontologische Zeitschrift.81(2): 174–180.doi:10.1007/BF02988391.S2CID129076419.Retrieved28 December2021.
- ^Tykoski, R. S.; Forster, C. A.; Rowe, T.; Sampson, S. D.; Munyikwa, D. (2002)."A furcula in the coelophysid theropod Syntarsus [Now Megapnosaurus]".Journal of Vertebrate Paleontology.22(3): 728–733.doi:10.1671/0272-4634(2002)022[0728:AFITCT]2.0.CO;2.S2CID39088559.Retrieved28 December2021.
- ^abJadoul, Flavio; Galli, M. T.; Calabrese, Lorenzo; Gnaccolini, Mario (2005)."Stratigraphy of Rhaetian to Lower Sinemurian carbonate platforms in western Lombardy (Southern Alps, Italy): paleogeographic implications".Rivista Italiana di Paleontologia e Stratigrafia.111(2): 285–303.Retrieved28 December2021.
- ^abcKalin, O.; DM, T. (1977)."Sedimentation und Paläotektonik in den westlichen Südalpen: Zur triasisch-jurassischen Geschichte des Monte Nudo-Beckens".Eclogae Geologicae Helvetiae.70(2): 295.Retrieved28 December2021.
- ^Leuzinger, P. (1925).Geologische Beschreibung des Monte Campo dei Fiori u. der Sedimentzone Luganersee-Valcuvia.Russy, FR, Switzerland: Buchdruckerei Emil Birkhäuse.
- ^Wiedenmayer, F. (1963).Obere Trias bis mittlerer Lias zwischen Saltrio und Tremona (Lombardische Alpen). Die Wechselbeziehungen zwischen Stratigraphie, Sedimentologie und syngenetischer Tektonik. Dissertation(1 ed.). Löbnitz: Basel, Birkhäuser.