Since the late 1980s in the Venezuelan state of Táchira, remains of dinosaurs have been uncovered at a road-cut between La Grita and Seboruco. Most of these belonged to a small herbivore that in 2014 was described as Laquintasaura. However, included in the discoveries were some theropod teeth, indicating a predator must have been present. In 2013, this was affirmed by the discovery of some theropod bones.[1]
In 2014, the type speciesTachiraptor admirabilis was named and described by Max Cardoso Langer, Ascanio D. Rincón, Jahandar Ramezani, Andrés Solórzano and Oliver Rauhut.[1]
The description was based on two fossils, found in a layer of the La Quinta Formation dating from the Early JurassicHettangian stage.[1] The region was once part of the equatorial belt of the ancient supercontinent of Pangaea.[3] A maximum age of 200.72 ± 0.32 million years ago has been confidently established, but due to the limits of zirconradiometric dating, a precise minimum estimate is not known; the actual age could be considerably younger. Both fossils are from the same location, but assumed to represent two individuals. One of these was the holotype specimen, IVIC-P-2867. It consists of a nearly complete right tibia or shinbone. The second fossil was referred to Tachiraptor admirabilis on the assumption that only one species of neotheropod of such a size was present in the La Quinta Formation. It is specimen IVIC-P-2868, consisting of the damaged upper half of a left ischium, a bone of the pelvis.[1]
EtymologyEdit
The generic name was derived from that of the state of Táchira, where it was discovered, combined with the Latin word for thief, raptor. The specific nameadmirabilis was chosen in reference to the Admirable Campaign of 1813, conducted by Simón Bolívar, for which the type locality of La Grita was of strategic importance.[1]
DescriptionEdit
Tachiraptor was a small bipedal predator. The shinbone has a length of about 25 cm (9.8 in); from this, the total body length of the animal has been deduced at just over 1.5 m (4.9 ft).[1][4]
The authors established a number of distinguishing traits. One of these is a possible autapomorphy, a unique evolutionary innovation shown just by Tachiraptor. It pertains to the profile, seen from above, of the upper surface of the shinbone. Such surfaces generally have two projections, corners jutting out to behind, left and right. In Tachiraptor the outer projection, at the side of the fibula, has a rear edge making a sharp angle with the outer edge. This way a uniquely sharp point is formed which, uniquely also, extends further to behind than the inner projection at the opposite side.[1]
Apart from the autapomorphy, a unique combination of, in themselves not unique, traits was also demonstrated. The bottom surface of the shinbone was, in its transverse width, about 1.5 times as wide as the longitudinal distance (measured from front to rear). In dinosaurs in general, the lower front of the shinbone is covered by the talus bone. A ridge on the front surface demarcates the upper limit of this area. In Tachiraptor this ridge ran obliquely at an angle of about 35° to the lower edge of the shinbone, covering a vertical distance of about a quarter to a third of the lower shinbone height. At its lower end, this ridge slightly curved upwards, being at this point close to the outer edge of the shinbone, at about a fifth of its transverse width. The shinbone extends to below in two bumps, left and right. When seen from the front, with Tachiraptor a line drawn between the bumps made an angle of 80° with the vertical axis of the bone.[1]
PhylogenyEdit
The study describing Tachiraptor performed a cladistic analysis, establishing its probable evolutionary relationships (phylogeny) by computing an evolutionary tree assuming the fewest evolutionary changes. This analysis showed that Tachiraptor was a basal member of the Neotheropoda, the subgroup encompassing all but the earliest theropods. It thus was placed low in the evolutionary tree of the neotheropods. Tachiraptor was part of the stem leading to the Averostra, the group all theropods belong to from the Middle Jurassic onwards, including the birds. Being a sister species of the Averostra, it was described as a "stem-averostran". This made the discovery of Tachiraptor especially important, because before 2014, there were no unequivocal stem-averostrans known at all. Tachiraptor thus reduced their ghost lineage (an inferred though yet unproven line of descent) by twenty-five million years.[1]
Tachiraptor also contributed to a greater knowledge of evolution by confirming that the equatorial zone of the supercontinent Pangea played an important role in the development of early dinosaurs, as already shown by the discovery of Laquintasaura.[1]
PaleoenvironmentEdit
Tachiraptor hails from the La Quinta Formation of northern South America, in what is now Colombia and Venezuela, and was found in the Venezuelan part of the formation. The La Quinta environment is interpreted as a tropical lowland forest. Its location and time suggests eusauropods reached a broad distribution before the breakup of Pangaea and the Toarcian faunal turnover.[5] Other dinosaurs from this formation include the eusauropod Perijasaurus, from Colombia, and the ornithischian Laquintasaura, from Venezuela.
ReferencesEdit
^ abcdefghijkLanger, Max C.; Rincón, Ascanio D.; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W.M. (8 October 2014). "New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes". Royal Society Open Science. Royal Society. 1 (2): 140–184. Bibcode:2014RSOS....140184L. doi:10.1098/rsos.140184. PMC4448901. PMID 26064540.
^Hannah Osborne (9 October 2014). "Dinosaur Species Discovered: Tachiraptor admirabilis was T-Rex's Tiny Ancestor from Venezuela". International Business Times. Retrieved 8 December 2014.
^ abCharles Q. Choi (7 October 2014). "Newfound South American Predator Snacked on Little Dinosaurs". LiveScience. Retrieved 8 December 2014.
^Sid Perkins (7 October 2014). "New meat-eating dinosaur lived in the wake of a mass extinction". Science News. Retrieved 8 December 2014.
^Rincón, Aldo F.; Raad Pájaro, Daniel A.; Jiménez Velandia, Harold F.; Ezcurra, Martín D.; Wilson Mantilla, Jeffrey A. (2022). "A sauropod from the Lower Jurassic La Quinta Formation (Dept. Cesar, Colombia) and the initial diversification of eusauropods at low latitudes". Journal of Vertebrate Paleontology. 42: e2077112. doi:10.1080/02724634.2021.2077112. S2CID 251501541.
October 20, 2023
tachiraptor, thief, táchira, genus, carnivorous, theropod, dinosaurs, found, early, jurassic, period, quinta, formation, venezuela, includes, species, admirabilis, described, from, fossilized, tibia, ischium, they, were, small, bipedal, dinosaurs, with, deduce. Tachiraptor thief of Tachira is a genus of carnivorous theropod dinosaurs found in the early Jurassic period La Quinta Formation of Venezuela It includes one species Tachiraptor admirabilis described from a fossilized tibia and ischium They were small bipedal dinosaurs with a deduced total body length of just over 1 5 m 4 9 ft 1 They were likely generalist predators preying on smaller vertebrates like other dinosaurs or lizards 2 3 TachiraptorTemporal range Early Jurassic 201 46 200 36 Ma PreꞒ Ꞓ O S D C P T J K Pg N HettangianIVIC P 2687 the holotype right tibia and IVIC P 2868 the referred left ischiumScientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClade DinosauriaClade SaurischiaClade TheropodaClade NeotheropodaGenus TachiraptorLanger Rincon Ramezani Solorzano amp Rauhut 2014Species T admirabilisBinomial name Tachiraptor admirabilisLanger Rincon Ramezani Solorzano amp Rauhut 2014 Contents 1 Discovery 2 Etymology 3 Description 4 Phylogeny 5 Paleoenvironment 6 ReferencesDiscovery Edit nbsp Tachiraptor admirabilis type locality in VenezuelaSince the late 1980s in the Venezuelan state of Tachira remains of dinosaurs have been uncovered at a road cut between La Grita and Seboruco Most of these belonged to a small herbivore that in 2014 was described as Laquintasaura However included in the discoveries were some theropod teeth indicating a predator must have been present In 2013 this was affirmed by the discovery of some theropod bones 1 In 2014 the type species Tachiraptor admirabilis was named and described by Max Cardoso Langer Ascanio D Rincon Jahandar Ramezani Andres Solorzano and Oliver Rauhut 1 The description was based on two fossils found in a layer of the La Quinta Formation dating from the Early Jurassic Hettangian stage 1 The region was once part of the equatorial belt of the ancient supercontinent of Pangaea 3 A maximum age of 200 72 0 32 million years ago has been confidently established but due to the limits of zircon radiometric dating a precise minimum estimate is not known the actual age could be considerably younger Both fossils are from the same location but assumed to represent two individuals One of these was the holotype specimen IVIC P 2867 It consists of a nearly complete right tibia or shinbone The second fossil was referred to Tachiraptor admirabilis on the assumption that only one species of neotheropod of such a size was present in the La Quinta Formation It is specimen IVIC P 2868 consisting of the damaged upper half of a left ischium a bone of the pelvis 1 Etymology EditThe generic name was derived from that of the state of Tachira where it was discovered combined with the Latin word for thief raptor The specific name admirabilis was chosen in reference to the Admirable Campaign of 1813 conducted by Simon Bolivar for which the type locality of La Grita was of strategic importance 1 Description EditTachiraptor was a small bipedal predator The shinbone has a length of about 25 cm 9 8 in from this the total body length of the animal has been deduced at just over 1 5 m 4 9 ft 1 4 The authors established a number of distinguishing traits One of these is a possible autapomorphy a unique evolutionary innovation shown just by Tachiraptor It pertains to the profile seen from above of the upper surface of the shinbone Such surfaces generally have two projections corners jutting out to behind left and right In Tachiraptor the outer projection at the side of the fibula has a rear edge making a sharp angle with the outer edge This way a uniquely sharp point is formed which uniquely also extends further to behind than the inner projection at the opposite side 1 Apart from the autapomorphy a unique combination of in themselves not unique traits was also demonstrated The bottom surface of the shinbone was in its transverse width about 1 5 times as wide as the longitudinal distance measured from front to rear In dinosaurs in general the lower front of the shinbone is covered by the talus bone A ridge on the front surface demarcates the upper limit of this area In Tachiraptor this ridge ran obliquely at an angle of about 35 to the lower edge of the shinbone covering a vertical distance of about a quarter to a third of the lower shinbone height At its lower end this ridge slightly curved upwards being at this point close to the outer edge of the shinbone at about a fifth of its transverse width The shinbone extends to below in two bumps left and right When seen from the front with Tachiraptor a line drawn between the bumps made an angle of 80 with the vertical axis of the bone 1 Phylogeny EditThe study describing Tachiraptor performed a cladistic analysis establishing its probable evolutionary relationships phylogeny by computing an evolutionary tree assuming the fewest evolutionary changes This analysis showed that Tachiraptor was a basal member of the Neotheropoda the subgroup encompassing all but the earliest theropods It thus was placed low in the evolutionary tree of the neotheropods Tachiraptor was part of the stem leading to the Averostra the group all theropods belong to from the Middle Jurassic onwards including the birds Being a sister species of the Averostra it was described as a stem averostran This made the discovery of Tachiraptor especially important because before 2014 there were no unequivocal stem averostrans known at all Tachiraptor thus reduced their ghost lineage an inferred though yet unproven line of descent by twenty five million years 1 Tachiraptor also contributed to a greater knowledge of evolution by confirming that the equatorial zone of the supercontinent Pangea played an important role in the development of early dinosaurs as already shown by the discovery of Laquintasaura 1 Paleoenvironment EditTachiraptor hails from the La Quinta Formation of northern South America in what is now Colombia and Venezuela and was found in the Venezuelan part of the formation The La Quinta environment is interpreted as a tropical lowland forest Its location and time suggests eusauropods reached a broad distribution before the breakup of Pangaea and the Toarcian faunal turnover 5 Other dinosaurs from this formation include the eusauropod Perijasaurus from Colombia and the ornithischian Laquintasaura from Venezuela References Edit a b c d e f g h i j k Langer Max C Rincon Ascanio D Ramezani Jahandar Solorzano Andres Rauhut Oliver W M 8 October 2014 New dinosaur Theropoda stem Averostra from the earliest Jurassic of the La Quinta formation Venezuelan Andes Royal Society Open Science Royal Society 1 2 140 184 Bibcode 2014RSOS 140184L doi 10 1098 rsos 140184 PMC 4448901 PMID 26064540 Hannah Osborne 9 October 2014 Dinosaur Species Discovered Tachiraptor admirabilis was T Rex s Tiny Ancestor from Venezuela International Business Times Retrieved 8 December 2014 a b Charles Q Choi 7 October 2014 Newfound South American Predator Snacked on Little Dinosaurs LiveScience Retrieved 8 December 2014 Sid Perkins 7 October 2014 New meat eating dinosaur lived in the wake of a mass extinction Science News Retrieved 8 December 2014 Rincon Aldo F Raad Pajaro Daniel A Jimenez Velandia Harold F Ezcurra Martin D Wilson Mantilla Jeffrey A 2022 A sauropod from the Lower Jurassic La Quinta Formation Dept Cesar Colombia and the initial diversification of eusauropods at low latitudes Journal of Vertebrate Paleontology 42 e2077112 doi 10 1080 02724634 2021 2077112 S2CID 251501541 Retrieved from https en wikipedia org w index php title Tachiraptor amp oldid 1175790274, wikipedia, wiki, book, books, library,
