Alwalkeria
 | It has been suggested that Alickmeron be merged into this article. (Discuss) Proposed since September 2025. |
| Alwalkeria Temporal range: Late Triassic,
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Scientific classification 
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Genus: | †Alwalkeria Chatterjee & Creisler, 1994 |
| Species: | †A. maleriensis
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| Binomial name | |
| †Alwalkeria maleriensis (Chatterjee, 1987)
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| Synonyms | |
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Alwalkeria (/ˌælwɔːˈkɪəriə/; "for Alick Walker") is an extinct genus of basal saurischian dinosaur from the Late Triassic Lower Maleri Formation of India.
History and classification
[edit]In 1987, Sankar Chatterjee named Walkeria maleriensis as a new genus and species of podokesaurid theropod dinosaurs based on specimen ISI R 306, which includes a partial skull, around 28 vertebrae, a proximal left femur, a distal right femur, and an astragalus (ankle bone). The specimen was recovered in the Godavari Valley locality from the Maleri Formation of Andhra Pradesh, India. The remains were collected by Chatterjee in 1974 in red mudstone that was deposited during the Carnian stage of the Triassic period, approximately 235 to 228 million years ago. The specimen is housed in the collection of the Indian Statistical Institute, in Kolkata, India.
The generic name, Walkeria, was proposed in honor of British paleontologist Alick Walker. The specific name, maleriensis, is a reference to the Lower Maleri Formation, in southern India, where its fossils were found. Chatterjee described the taxon as a basal theropod.[1] Since the original generic name was found to be preoccupied by a bryozoan, the new replacement generic name Alwalkeria was created in 1994 by Chatterjee and Ben Creisler.[2]
In 1996, Loyal et al. agreed with a theropod identity for the type material.[3] Paul (1988) understood Alwalkeria as a link between herrerasaurids and the genus Protoavis, and hence assigned it to Herrerasauridae based on features of the femur.[4] However, Langer (2004) and Martínez and Alcober (2009), observed that Alwalkeria was too primitive to be a theropod and considered it a basal saurischian.[5][6]
Chimeric identity
[edit]In 2005, Rauhut and Remes found Alwalkeria to be a chimera, with the anterior skull referable to a crurotarsan, and the vertebrae referable to various other ancient reptiles including Prolacertiformes; however, they claimed the femur and the astragalus were clearly dinosaurian, with the latter possessing saurischian characteristics.[7] In 2011, Novas and colleagues argued that Alwalkeria remains valid on the basis of an unusual morphology of its femur and an astragalus with a conservative morphology more similar to that of basal dinosaurs.[8] In 2016, Lecuona, Ezcurra & Irmis reiterated the chimaeric nature of the Alwalkeria holotype, noting that the skull material could be referred to the Crocodylomorpha. They also observed that the distal femur was more consistent with the morphology of pseudosuchians, leading them to identify this bone fragment as an indeterminate representative of that clade. The vertebrae lack anatomical features allowing for a precise identification, dinosaur, pseudosuchian, or otherwise.[9]
In 2025, Sen & Ray determined the partial femora belonged to a novel representative of the Lagerpetidae, which they named Alickmeron maleriensis. The authors did not classify the astagalus within the genus Alwalkeria, but rather as indeterminate saurischian comparable in morphology to an unnamed Argentinan herrerasaurid.[10]
Paleoecology
[edit]The Maleri Formation has been interpreted as being the site of an ancient lake or river. Material of the sauropodomorphs Jaklapallisaurus and Nambalia and the herrerasaurian Maleriraptor have been found in the Upper Maleri Formation, as well as intermediate prosauropod remains.[11]
References
[edit]- ^ Chatterjee, S. 1987. A new theropod dinosaur from India with remarks on the Gondwana-Laurasia connection in the Late Cretaceous. In: McKenzie, G.D. (Ed.). Gondwana Six: Stratigraphy, Sedimentology, and Paleontology. Geophysical Monograph 41. Washington, D.C.: American Geophysical Union. Pp. 183–189.
- ^ Chatterjee, S. & Creisler, B.S. 1994. Alwalkeria (Theropoda) and Morturneria (Plesiosauria), new names for preoccupied Walkeria Chatterjee, 1987, and Turneria Chatterjee and Small, 1989. Journal of Vertebrate Paleontology 14(1): 142.
- ^ R. S. Loyal, A. Khosla, and A. Sahni. 1996. Gondwanan dinosaurs of India: affinities and palaeobiogeography. Memoirs of the Queensland Museum 39(3):627-638
- ^ Paul, 1988. Predatory dinosaurs of the world. Simon and Schuster, New York. A New York Academy of Sciences Book. 464 pp.
- ^ Langer, M.C. 2004. Basal Saurischia. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 25–46.
- ^ R. N. Martínez and O. A. Alcober. 2009. A basal sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the early evolution of Sauropodomorpha. PLoS ONE 4(2 (e4397)):1-12
- ^ Remes and Rauhut, 2005. The oldest Indian dinosaur Alwalkeria maleriensis Chatterjee revised: a chimera including remains of a basal saurischian. in Kellner, Henriques and Rodrigues (eds). II Congresso Latino-Americano de Paleontologia de Vertebrados, Boletim de Resumos. Museu Nacional, Rio de Janeiro. 218.
- ^ Novas, Fernando E.; Ezcurra, Martín D.; Chatterjee, Sankar; Kutty, T.S. (2011). "New dinosaur species from the Upper Triassic Upper Maleri and Lower Dharmaram formations of central India". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 101 (3–4): 333–349. doi:10.1017/S1755691011020093.
- ^ Lecuona, Agustina; Ezcurra, Martín D.; Irmis, Randall B. (2016-10-03). Angielczyk, Kenneth (ed.). "Revision of the early crocodylomorph Trialestes romeri (Archosauria, Suchia) from the lower Upper Triassic Ischigualasto Formation of Argentina: one of the oldest‐known crocodylomorphs". Papers in Palaeontology. 2 (4): 585–622. doi:10.1002/spp2.1056. hdl:11336/66393. ISSN 2056-2799.
- ^ Sen, Sulagna; Ray, Sanghamitra (2025-09-29). "Taxonomic reassessment of archosaurs with dinosaurian affinities from the lower fauna of the Upper Triassic Maleri Formation of India and their significance". Journal of Vertebrate Paleontology. doi:10.1080/02724634.2025.2546434. ISSN 0272-4634.
- ^ Ezcurra, Martín D.; Garcia, Maurício Silva; Novas, Fernando E.; Müller, Rodrigo Temp; Agnolín, Federico L.; Chatterjee, Sankar (2025-05-07). "A new herrerasaurian dinosaur from the Upper Triassic Upper Maleri Formation of south-central India". Royal Society Open Science. 12 (5). doi:10.1098/rsos.250081. ISSN 2054-5703. PMC 12077243.
Bibliography
[edit]- Norman, D.B. 1990. Problematic Theropods: Coelurosaurs. In: Weishampel, D.B., Dodson, P. & Osmolska, H. (Eds.). The Dinosauria (1st Edition). Berkeley: University of California Press. Pp. 280–305.
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