Condorchelys

Condorchelys
Temporal range: Middle Toarcian
~179.17–178.07 Ma
↓
[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Pantestudines
Clade: Testudinata
Clade: Rhaptochelydia
Clade: Mesochelydia
Genus: †Condorchelys
Sterli 2008
Species:
†C. antiqua
Binomial name
†Condorchelys antiqua
Sterli 2008

Condorchelys was a genus of stem turtle from Early Jurassic (Middle Toarcian) Cañadon Asfalto Formation of Argentina. Condorchelys represents the oldest Jurassic-aged Turtle from South America, with only one species described, Condorchelys antiqua.[2]

Discovery

The holotype of Condorchelys was first discovered on the "Queso Rallado" locality, 5.5 km from the west of Cerro Cóndor village in the Chubut Province, Argentina, from layers of the Cañadón Asfalto Formation, back then considered to be Middle or Late Jurassic in age,[2] though modern re-datations confirmed a Toarcian (Early Jurassic) Age.[1] The holotype, MPEF-PV1152 is a basicranium. Other specimens where originally referred, including MPEF-PV 1783A-B (neural series, costal bones and thoracic vertebrae), MPEF-PV 1998 (basicranium), MPEF-PV 3131 (basicranium with skull roof), MPEF-PV 3132 (lmost complete carapace), MPEF-PV 3133 (pectoral girdle), MPEF-PV 3134 (entoplastron), MPEF-PV 3135 (pelvic girdle) and MPEF-PV 3136 (left hyoplastron).[2] Additional specimens where later recovered in Queso Rallado, including both cranial and postcranial remains.[3] And then in other outcrops like Cañadon Bagual, "Chucrut" and "Canela".[4] The name was coined in reference to nearby Cerro Cóndor village, while the species name antiqua from the Latin word for old, ancient.[2]

Description

Condorchelys is overall similar to the genera Kayentachelys aprix and Indochelys spatulata, yet lacking pterygoid teeth and a V-shaped suprapygal 2.[5] The skull roof exhibits ornamentation formed by ridges and grooves similar to the ones seen in Kayentachelys. The carapace is oval, about 21x16 cm in one of the referred specimens, being longer than wider, ornamented with small pits and grooves.[3][5] Shell microstructure, showing bones with a low degree of compactness/homogenization of cortical and cancellous shell areas, suggests an aquatic life style.[6]

Phylogeny

The original description cladistic analysis allocated C. antiqua as a stem turtle, reinforcing previous placements of other stem taxa, including Kayentachelys, Indochelys & Condorchelys as a group, and the Middle Jurassic Laurasian genus Heckerochelys as a close outgrup.[2] Latter on the basis of new material several phylogenetic analyses where done, finding C. antiqua either a stem member of Testudines or in several positions in Mesochelydia, in any case still grouping with Kayentachelys & Indochelys.[3]

References

  1. ^ a b Fantasia, A.; Föllmi, K. B.; Adatte, T.; Spangenberg, J. E.; Schoene, B.; Barker, R. T.; Scasso, R. A. (2021). "Late Toarcian continental palaeoenvironmental conditions: An example from the Canadon Asfalto Formation in southern Argentina". Gondwana Research. 89 (1): 47–65. Bibcode:2021GondR..89...47F. doi:10.1016/j.gr.2020.10.001. S2CID 225120452. Retrieved 27 August 2021.
  2. ^ a b c d e Sterli, J (2008), "A new, nearly complete stem turtle from the Jurassic of South America with implications for turtle evolution", Biology Letters, 4 (3): 286–289, doi:10.1098/rsbl.2008.0022, PMC 2610044, PMID 18331974, retrieved 2019-03-01
  3. ^ a b c Sterli, J.; De La Fuente, M. S.; Rougier, G. W. (2018). "New remains of Condorchelys antiqua (Testudinata) from the Early-Middle Jurassic of Patagonia: anatomy, phylogeny, and paedomorphosis in the early evolution of turtles". Journal of Vertebrate Paleontology. 38 (4): (1)-(17). Bibcode:2018JVPal..38....1S. doi:10.1080/02724634.2018.1480112. hdl:11336/99525. Retrieved 17 December 2023.
  4. ^ Sterli, J.; Vlachos, E.; Puerta, P.; Oriozabala, C.; Krause, M. (2021). "Contribution to the diversity of the fossil record of turtles (Testudinidata) from Chubut province (Argentina) and its significance in understanding the evolution of turtles in southern South America". Publicación Electrónica de la Asociación Paleontológica Argentina. 21 (1): 118–160. Retrieved 31 March 2022.
  5. ^ a b Sterli, J.; De La Fuente, M. S. (2010). "Anatomy of C ondorchelys antiqua Sterli, 2008, and the origin of the modern jaw closure mechanism in turtles". Journal of Vertebrate Paleontology. 30 (2): 351–366. Bibcode:2010JVPal..30..351S. doi:10.1080/02724631003617597. Retrieved 17 December 2023.
  6. ^ Cerda, I. A; Sterli, J.; Scheyer, T. M. (2016). "Bone shell microstructure of Condorchelys antiqua Sterli, 2008, a stem turtle from the Jurassic of Patagonia". Comptes Rendus Palevol. 15 (1–2): 128–141. Bibcode:2016CRPal..15..128C. doi:10.1016/j.crpv.2015.01.004. hdl:11336/46091. Retrieved 17 December 2023.


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