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An enigmatic plant-eating theropod from the Late Jurassic period of Chile


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Theropod dinosaurs were the dominant predators in most Mesozoic era terrestrial ecosystems1. Early theropod evolution is currently interpreted as the diversification of various carnivorous and cursorial taxa, whereas the acquisition of herbivorism, together with the secondary loss of cursorial adaptations, occurred much later among advanced coelurosaurian theropods1,2. A new, bizarre herbivorous basal tetanuran from the Upper Jurassic of Chile challenges this conception. The new dinosaur was discovered at Aysén, a fossil locality in the Upper Jurassic Toqui Formation of southern Chile (General Carrera Lake)3,4. The site yielded abundant and exquisitely preserved three-dimensional skeletons of small archosaurs. Several articulated individuals of Chilesaurus at different ontogenetic stages have been collected, as well as less abundant basal crocodyliforms, and fragmentary remains of sauropod dinosaurs (diplodocids and titanosaurians).

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Figure 1: Skeletal anatomy of Chilesaurus diegosuarezi gen. et sp. nov.
Figure 2: Selected cranial bones and teeth of Chilesaurus diegosuarezi gen. et sp. nov. (SNGM-1935).
Figure 3: Phylogenetic relationships of Chilesaurus diegosuarezi gen. et sp. nov. among main dinosaur clades and its plots in the theropod morphospaces.

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  • 17 June 2015

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We thank P. Barrett, A. Milner and R. Butler for comments on early versions of this manuscript. We are grateful to C. Alsina, M. Milani, R. Stoll and M. Aranciaga for field assistance and technical preparation of Chilesaurus specimens. G. Lio executed the silhouette of Chilesaurus in Fig. 1. C. Burke offered support to conduct fieldwork and technical preparation of the specimens. We are indebted to the Agencia Nacional de Promoción Científica y Tecnológica (PICT 2010-066 to F.E.N.) and the Fondo Nacional de Desarrollo Científico y Tecnológico (no. 1121140 and 1030162 to M.S.) for continuing financial assistance.

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Authors and Affiliations



F.E.N., L.S., M.S., F.L.A., M.D.E., N.R.C., A.O.V. and D.R.-R. designed the study, collected data, performed the comparative and analytical work, and wrote the paper. R.d.l.C. and M.P.I. collected data and contributed to the writing and discussion.

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Correspondence to Fernando E. Novas.

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The authors declare no competing financial interests.

Additional information

Data have been deposited in ZooBank under Life Science Identifier (LSID)

Extended data figures and tables

Extended Data Figure 1 Holotype of Chilesaurus diegosuarezi gen. et sp. nov. (SNGM-1935) as it was found in the field.

Cd, caudal vertebrae; Cv, cervical vertebrae; Dv, dorsal vertebrae; Lf, left forelimb; Lfem, left femur; Lsc, left scapulocoracoid; Ltib, left tibia; Rf, right forelimb; Sk, skull.

Extended Data Figure 2 Selected skull bones of Chilesaurus diegosuarezi gen. et sp. nov. (SNGM-1935; holotype).

a, Right frontal in dorsal view; b, right postorbital in lateral view; c, incomplete right (?) maxilla in lateral view; d, right dentary in medial view. al, alveolus; ao, antorbital opening; or, orbital rim; t, teeth; tf, lower temporal fossa rim.

Extended Data Figure 3 Scapular girdle and selected forelimb bones of Chilesaurus diegosuarezi gen. et sp. nov. a,

b, Left scapula and coracoid (SNGM-1938) in lateral (a) and posterior (b) views. c, Left humerus (SNGM-1938) in anterior view; d, left radius (SNGM-1935, holotype) in lateral view; and e, left ulna (SNGM-1935, holotype) in lateral view. cf, coracoid foramen; dp, deltopectoral crest; gl, glenoid cavity; ol, olecranon process.

Extended Data Figure 4 Selected hindlimb elements of Chilesaurus diegosuarezi gen. et sp. nov. a,

b, Right femur (SNGM-1935) in anterior (a) and lateral (b) views. ce, Articulated right tibia and fibula (SNGM-1935) in posterior (c), medial (d) and proximal (e) views. at, anterior trochanter; cn, cnemial crest; f, fibula; fh, femoral head, 4t, fourth trochanter; gt, greater trochanter, ic, inner condyle; oc, outer condyle; t, tibia; tfc, tibiofibular crest.

Extended Data Figure 5 Bivariate plots showing the results of the morphospace occupation analysis of Chilesaurus diegosuarezi gen. et sp. nov. based on characters of different regions of the skeleton, taken from the modified data matrix and the first and second axes of the principal coordinate analysis.

ad, Bivariate plots using all the characters (a), cranial characters (b), hindlimb zeugopodium and stylopodium characters (c), and tarsal and pedal characters (d). The convex hulls represent different dinosauriform groups rather than statistically distinct clusters. Light grey polygon, non-neotheropod dinosauriforms; blue polygon, non-averostran neotheropods; green polygon, ceratosaurs; pink polygon, megalosauroids; dark grey polygon, allosauroids; light blue polygon, coelurosaurs; red dot, Chilesaurus.

Extended Data Table 1 Selected postcranial measurements of three specimens of Chilesaurus diegosuarezi gen. et sp. nov.

Supplementary information

Supplementary Information

This file contains Supplementary Text and Data, Supplementary Figures and additional references, which are divided into the following sections: Occurrence, age, and preservation of the holotype and referred specimens of Chilesaurus diegosuarezi gen. et sp. nov.; Phylogenetic analyses; and Morphospace analysis. (PDF 3286 kb)

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Novas, F., Salgado, L., Suárez, M. et al. An enigmatic plant-eating theropod from the Late Jurassic period of Chile. Nature 522, 331–334 (2015).

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