Letter | Published:

Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs

Nature volume 552, pages 395399 (21 December 2017) | Download Citation


Maniraptora includes birds and their closest relatives among theropod dinosaurs1,2,3,4,5. During the Cretaceous period, several maniraptoran lineages diverged from the ancestral coelurosaurian bauplan and evolved novel ecomorphologies, including active flight2, gigantism3, cursoriality4 and herbivory5. Propagation X-ray phase-contrast synchrotron microtomography of a well-preserved maniraptoran from Mongolia, still partially embedded in the rock matrix, revealed a mosaic of features, most of them absent among non-avian maniraptorans but shared by reptilian and avian groups with aquatic or semiaquatic ecologies6,7,8,9,10,11,12,13,14. This new theropod, Halszkaraptor escuilliei gen. et sp. nov., is related to other enigmatic Late Cretaceous maniraptorans from Mongolia15,16 in a novel clade at the root of Dromaeosauridae17. This lineage adds an amphibious ecomorphology to those evolved by maniraptorans: it acquired a predatory mode that relied mainly on neck hyperelongation for food procurement, it coupled the obligatory bipedalism of theropods with forelimb proportions that may support a swimming function, and it developed postural adaptations convergent with short-tailed birds.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    Saurischian monophyly and the origin of birds. Memoirs Cal. Acad. Sci. 8, 1–55 (1986)

  2. 2.

    in Mesozoic Birds: Above the Heads of Dinosaurs (eds & ) 3–30 (Univ. California Press, 2002)

  3. 3.

    , , , & A gigantic bird-like dinosaur from the Late Cretaceous of China. Nature 447, 844–847 (2007)

  4. 4.

    The arctometatarsalian pes, an unusual structure of the metatarsus of Cretaceous Theropoda (Dinosauria: Saurischia). J. Vertebr. Paleontol. 14, 480–519 (1995)

  5. 5.

    & Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution. Proc. Natl Acad. Sci. USA 108, 232–237 (2011)

  6. 6.

    Swimming capabilities of Mesozoic marine reptiles: implications for method of predation. Paleobiology 14, 187–205 (1988)

  7. 7.

    Skeletal morphology and relationships of the early Cretaceous side-necked turtle, Araripemys barretoi (Testudines: Pelomedusoides: Araripemydidae), from the Santana Formation of Brazil. J. Vertebr. Paleontol. 16, 20–33 (1996)

  8. 8.

    & Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey. Bull. Nat. Hist. Mus. Lond. (Geol.) 53, 11–70 (1997)

  9. 9.

    From fins to limbs to fins: limb evolution in fossil marine reptiles. Am. J. Med. Genet. 112, 236–249 (2002)

  10. 10.

    & in Fins into Limbs: Evolution, Development, and Transformation (ed. ) 310–322 (Univ. Chicago Press, 2007)

  11. 11.

    The structural mechanics and evolution of aquaflying birds. Biol. J. Linn. Soc. 99, 687–698 (2010)

  12. 12.

    , , , & Complex rostral neurovascular system in a giant pliosaur. Naturwissenschaften 101, 453–456 (2014)

  13. 13.

    , , , & Complex neuroanatomy in the rostrum of the Isle of Wight theropod Neovenator salerii. Sci. Rep. 7, 3749 (2017)

  14. 14.

    , , & Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians. PLoS ONE 12, e0172759 (2017)

  15. 15.

    Hulsanpes perlei n.g. n.sp. (Deinonychosauria, Saurischia, Dinosauria) from the Upper Cretaceous Barun Goyot Formation of Mongolia. Neues Jahrb. Geol. Paläontol. Monat. 7, 440–448 (1982)

  16. 16.

    , & Anatomy of Mahakala omnogovae (Theropoda: Dromaeosauridae), Tögrögiin Shiree, Mongolia. Am. Mus. Nov. 3722, 1–66 (2011)

  17. 17.

    , & A review of dromaeosaurid systematics and paravian phylogeny. Bull. Am. Mus. Nat. Hist. 371, 1–206 (2012)

  18. 18.

    , & A new dinosaur, Gallimimus bullatus n. gen., n. sp. (Ornithomimidae) from the Upper Cretaceous of Mongolia. Palaeontol. Pol. 27, 103–143 (1972)

  19. 19.

    & Osteology of Khaan mckennai (Oviraptorosauria: Theropoda). Bull. Am. Mus. Nat. Hist. 372, 1–77 (2012)

  20. 20.

    et al. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings. Nature 521, 70–73 (2015)

  21. 21.

    Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana. Peabody Mus. Nat. Hist. Bull. 30, 1–165 (1969)

  22. 22.

    , & The phylogenetic affinities of the bizarre Late Cretaceous Romanian theropod Balaur bondoc (Dinosauria, Maniraptora): dromaeosaurid or flightless bird? PeerJ 3, e1032 (2015)

  23. 23.

    , & The teeth of the unenlagiine theropod Buitreraptor from the Cretaceous of Patagonia, Argentina, and the unusual dentition of the Gondwanan dromaeosaurids. Acta Palaeontol. Pol. 56, 279–290 (2011)

  24. 24.

    et al. Piscivory in the feathered dinosaur Microraptor. Evolution 67, 2441–2445 (2013)

  25. 25.

    , , , & Plesiosaur swimming as interpreted from skeletal analysis and experimental results. Trans. Kans. Acad. Sci. 113, 1–34 (2010)

  26. 26.

    Comparison of forelimb function between Deinonychus and Bambiraptor (Theropoda: Dromaeosauridae). J. Vertebr. Paleontol. 26, 897–906 (2006)

  27. 27.

    , & How do cormorants counter buoyancy during submerged swimming? J. Exp. Biol. 207, 2101–2114 (2004)

  28. 28.

    The evolution of femoral osteology and soft tissues on the line to extant birds (Neornithes). Zool. J. Linn. Soc. 131, 169–197 (2001)

  29. 29.

    & Locomotor modules and the evolution of avian flight. Evolution 50, 331–340 (1996)

  30. 30.

    , & TNT, a free program for phylogenetic analysis. Cladistics 24, 774–786 (2008)

Download references


We thank the European Synchrotron Radiation Facility for granting us beam time at ID19 and BM05 beamlines; Y. Pommery for his work on teeth segmentation; T. Hubin for photographs; A. Halamski and D. Madzia for information on Hulsanpes holotype; and M. Auditore for the skeletal reconstructions. U. Lefèvre and L. Van Bossuyt took conventional X-ray pictures at the Veterinary School of Liège University. Silhouettes in Fig. 4a were provided by D. Bonadonna and L. Panzarin and are used with their permission. The program TNT was made available by the sponsorship of the Willi Hennig Society.

Author information


  1. Geological and Palaeontological Museum ‘Giovanni Capellini’, I-40126 Bologna, Italy

    • Andrea Cau
  2. European Synchrotron Radiation Facility, F-38043 Grenoble, France

    • Vincent Beyrand
    • , Dennis F. A. E. Voeten
    • , Vincent Fernandez
    •  & Paul Tafforeau
  3. Department of Zoology and Laboratory of Ornithology, Palacký University, CS-40220 Olomouc, Czech Republic

    • Vincent Beyrand
    •  & Dennis F. A. E. Voeten
  4. Earth System Science – AMGC Vrije Universiteit Brussel, B-1050 Brussels, Belgium

    • Koen Stein
  5. Palaeontological Center, Mongolian Academy of Sciences, Ulaanbaatar 201-351, Mongolia

    • Rinchen Barsbold
  6. Institute of Palaeontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar 210-351, Mongolia

    • Khishigjav Tsogtbaatar
  7. Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada

    • Philip J. Currie
  8. Directorate Earth & History of Life, Royal Belgian Institute of Natural Sciences, B-1000 Brussels, Belgium

    • Pascal Godefroit


  1. Search for Andrea Cau in:

  2. Search for Vincent Beyrand in:

  3. Search for Dennis F. A. E. Voeten in:

  4. Search for Vincent Fernandez in:

  5. Search for Paul Tafforeau in:

  6. Search for Koen Stein in:

  7. Search for Rinchen Barsbold in:

  8. Search for Khishigjav Tsogtbaatar in:

  9. Search for Philip J. Currie in:

  10. Search for Pascal Godefroit in:


A.C. and P.G. designed the project. P.G. supervised the preparation of the specimen. P.T., V.B., D.F.A.E.V. and V.F. performed synchrotron scanning, data processing and segmentation, and created the 2D and 3D renderings. K.S. conducted the histological analysis. R.B., K.T. and P.J.C. provided information on Mongolian theropods and geological setting. A.C. conducted the phylogenetic analyses. A.C. wrote the manuscript with input from all other authors.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Andrea Cau.

Reviewer Information Nature thanks T. Holtz Jr and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file contains Supplementary Tables 1-2, Supplementary Text, Supplementary References and Supplementary Data – see contents page for details.

  2. 2.

    Life Sciences Reporting Summary

About this article

Publication history






Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.