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Bizarre dermal armour suggests the first African ankylosaur

Nature Ecology & Evolution volume 5, pages 1576–1581 (2021)Cite this article

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Abstract

Ankylosauria is a diverse clade of armoured dinosaurs whose members were important constituents of many Cretaceous faunas. Phylogenetic analyses imply that the clade diverged from its sister taxon, Stegosauria, during the late Early Jurassic, but the fossil records of both clades are sparse until the Late Jurassic (~150 million years ago). Moreover, Ankylosauria is almost entirely restricted to former Laurasian continents, with only a single valid Gondwanan taxon. Spicomellus afer gen. et sp. nov. appears to represent the earliest-known ankylosaur and the first to be named from Africa, from the Middle Jurassic (Bathonian–Callovian) of Morocco, filling an important gap in dinosaur evolution. The specimen consists of a rib with spiked dermal armour fused to its dorsal surface, an unprecedented morphology among extinct and extant vertebrates. The specimen reveals an unrealized morphological diversity of armoured dinosaurs during their early evolution, and implies the presence of an important but undiscovered Gondwanan fossil record.

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Fig. 1: Morphology and histology of Spicomellus afer, NHMUK PV R37412.
Fig. 2: Details of the histology of Spicomellus afer, NHMUK PV R37142.

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Data availability

All data associated with this paper are included in Extended Data. The specimen described in this study is reposited in the collections of the Natural History Museum, London, under specimen number NHMUK PV R37412. This published work and the nomenclatural acts it contains are registered with ZooBank (LSID: urn:lsid:zoobank.org:act:D12DDAB4-E164-411D-8406-B7B3DEC52F71LSID: urn:lsid:zoobank.org:act:D12DDAB4-E164-411D-8406-B7B3DEC52F71).

References

  1. Vickaryous, M. K., Maryańska, T. & Weishampel, D. B. in The Dinosauria (eds Weishampel, D. B. et al.) 363–392 (Univ. California Press, 2004).

  2. Thompson, R. S., Parish, J. C., Maidment, S. C. R. & Barrett, P. M. Phylogeny of the ankylosaurian dinosaurs. J. Syst. Palaeontol. 10, 301–312 (2012).

    Article  Google Scholar 

  3. Arbour, V. M. & Currie, P. J. Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs. J. Syst. Palaeontol. 14, 385–444 (2016).

    Article  Google Scholar 

  4. Maidment, S. C. R., Raven, T. J., Ouarhache, D. & Barrett, P. M. North Africa’s first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity. Gondwana Res. 77, 82–97 (2020).

    Article  Google Scholar 

  5. Galton, P. M. Sarcolestes leedsi Lydekker, an ankylosaurian dinosaur from the Middle Jurassic of England. Neues Jahrb. Geol. Palaeontol. Monatsh. 1983, 141–155 (1983).

    Google Scholar 

  6. Leahey, L., Molnar, R. E., Carpenter, K., Witmer, L. M. & Salisbury, S. W. Cranial osteology of the ankylosaurian dinosaur formerly known as Minmi sp. (Ornithischia: Thyreophora) from the Lower Cretaceous Allaru Mudstone of Richmond, Queensland, Australia. PeerJ 3, e1475 (2015).

    Article  PubMed  PubMed Central  Google Scholar 

  7. Owen, R. Report on British fossil reptiles. Rep. Brit. Assoc. Adv. Sci. 11, 60–204 (1842).

    Google Scholar 

  8. Seeley, H. G. On the classification of the fossil animals commonly named Dinosauria. Proc. R. Soc. Lond. 43, 258–265 (1888).

    Google Scholar 

  9. Osborn, H. F. Two Lower Cretaceous dinosaurs of Mongolia. Am. Mus. Novit. 95, 1–10 (1923).

    Google Scholar 

  10. de Buffrénil, V., Farlow, J. O. & de Ricqlès, A. Growth and function of Stegosaurus plates: evidence from bone histology. Paleobiology 12, 459–473 (1986).

    Article  Google Scholar 

  11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874–893 (2004).

    Article  Google Scholar 

  12. Scheyer, T. M., Sander, P. M., Joyce, W. G., Bohme, W. & Witzel, U. A plywood structure in the shell of fossil and living soft-shelled turtles (Trionychidae) and its evolutionary implications. Org. Divers. Evol. 7, 136–144 (2007).

    Article  Google Scholar 

  13. Berkovitz, B. & Shellis, R. P. The Teeth of Non-mammalian Vertebrates (Academic Press, 2017).

  14. Schnetz, L., Pfaff, C. & Kriwet, J. Tooth development and histology patterns in lamniform sharks (Elasmobranchii, Lamniformes) revisited. J. Morphol. 277, 1584–1598 (2016).

    Article  PubMed  Google Scholar 

  15. Jambura, P. L. et al. Micro-computed tomography imaging reveals the development of a unique tooth mineralization pattern in mackerel sharks (Chondrichthyes, Lamniformes) in deep time. Sci. Rep. 9, 9652 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  16. Jambura, P. L. et al. Evolutionary trajectories of tooth histology patterns in modern sharks (Chondrichthyes, Elasmobranchii). J. Anat. 236, 753–771 (2020).

    Article  PubMed  Google Scholar 

  17. Reid, R. E. H. Bone histology of the Cleveland-Lloyd dinosaurs and of dinosaurs in general, part 1: introduction to bone tissues. BYU Geol. Stud. 41, 25–72 (1996).

    Google Scholar 

  18. Main, R. P., de Ricqlès, A., Horner, J. R. & Padian, K. The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs. Paleobiology 31, 291–314 (2005).

    Article  Google Scholar 

  19. Dubansky, B. H. & Dubansky, B. D. Natural development of dermal ectopic bone in the American alligator (Alligator mississippiensis) resembles heterotopic ossification disorders in humans. Anat. Rec. 301, 56–76 (2018).

    Article  Google Scholar 

  20. Kirby, A. et al. A comparative histological study of the osteoderms in the lizards Heloderma suspectum (Squamata: Helodermatidae) and Varanus komodoensis (Squamata: Varanidae). J. Anat. 236, 1035–1043 (2020).

    Article  PubMed  PubMed Central  Google Scholar 

  21. Shadwick, R. E., Russell, A. P. & Lauff, R. F. The structure and mechanical design of rhinoceros dermal armour. Philos. Trans. R. Soc. Lond. B 337, 419–428 (1992).

    Article  CAS  Google Scholar 

  22. Hall, B. K. Bones and Cartilage, Development and Evolutionary Skeletal Biology (Elsevier, 2015).

    Google Scholar 

  23. Galton, P. M. & Upchurch, P. in The Dinosauria (eds Weishampel, D. B. et al.) 343–362 (Univ. California Press, 2004).

  24. Barrett, P. M., Clarke, J. B., Brinkman, D. B., Chapman, S. D. & Ensom, P. C. Morphology, histology and identification of the ‘granicones’ from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England. Cretac. Res. 23, 279–295 (2002).

    Article  Google Scholar 

  25. Burns, M. E. & Currie, P. J. External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance. J. Vertebr. Paleontol. 34, 835–851 (2014).

    Article  Google Scholar 

  26. Norman, D. B. Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoo. J. Linn. Soc. 191, 1–86 (2021).

    Article  Google Scholar 

  27. Scheyer, T. M., Syromyatnikova, E. V. & Danilov, I. G. Turtle shell bone and osteoderm histology of Mesozoic and Cenozoic stem-trionychian Adocidae and Nanhsiungchelyida (Crypodira: Adocusia) from Central Asia, Mongolia and North America. Foss. Rec. 20, 69–85 (2017).

    Article  Google Scholar 

  28. Cerda, I. A., Desojo, J. B. & Scheyer, T. M. Novel data on aetosaur (Archosauria: Pseudosuchia) osteoderm microanatomy and histology: palaeobiological implications. Palaeontology 61, 721–745 (2018).

    Article  Google Scholar 

  29. D’Emic, M. D., Wilson, J. A. & Chatterjee, S. The titanosaur (Dinosauria: Sauropoda) osteoderm record: review and first definitive specimen from India. J. Vertebr. Paleontol. 29, 165–177 (2009).

    Article  Google Scholar 

  30. Scheyer, T. M., Desojo, J. B. & Cerda, I. A. Bone histology of phytosaur, aetosaur, and other archosauriform osteoderms (Eureptilia, Archosauromorpha). Anat. Rec. 297, 240–260 (2014).

    Article  Google Scholar 

  31. Cerda, I. A., García, R. A., Powell, J. E. & Lopez, O. Morphology, microanatomy and histology of titanosaur (Dinosauria, Sauropoda) osteoderms from the Upper Cretaceous of Patagonia. J. Vertebr. Paleontol. 35, e905791 (2015).

    Article  Google Scholar 

  32. Stocker, M. R. & Butler, R. J. in Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin (eds Nesbitt, S. J. et al.) 91–117 (Geological Society, London, 2013).

  33. Desojo, J. B., et al. in Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin (eds Nesbitt, S. J. et al.) 203–239 (Geological Society, London, 2013).

  34. Gaffney, E. S. The comparative osteology of the Triassic turtle Proganochelys. Bull. Am. Mus. Nat. Hist. 194, 1–263 (1990).

    Google Scholar 

  35. Gorsack, E. & O’Connor, P. M. Time-calibrated models support congruency between Cretaceous continental rifting and titanosaurian evolutionary history. Biol. Lett. 12, 20151047 (2016).

    Article  Google Scholar 

  36. Maidment, S. C. R. Stegosauria: a historical review of the body fossil record and phylogenetic relationships. Swiss J. Geosci. 103, 199–210 (2010).

    Article  Google Scholar 

  37. Reichel, M., Schultz, C. L. & Soares, M. B. A new traversodontid cynodont (Therapsida, Eucynodontia) from the Middle Triassic Santa Maria Formation of Rio Grande do Sul, Brazil. Palaeontology 52, 229–250 (2009).

    Article  Google Scholar 

  38. Scheyer, T. M. & Sues, H. D. Expanded dorsal ribs in the Late Triassic pseudosuchian reptile Euscolosuchus olseni. J. Vertebr. Paleontol. 37, e1248768 (2017).

    Article  Google Scholar 

  39. Salgado, L. et al. A new primitive neornithischian dinosaur from the Jurassic of Patagonia with gut contents. Sci. Rep. 7, 42778 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  40. Molnar, R. E. & Wiffen, J. A Late Cretaceous polar dinosaur fauna from New Zealand. Cretac. Res. 15, 689–706 (1994).

    Article  Google Scholar 

  41. Coria, R. A. & Salgado, L. in The Armored Dinosaurs (ed. Carpenter, K.) 159–168 (Indiana Univ. Press, 2001).

  42. Nath, T. T., Yadagiri, P. & Moitra, A. K. First record of armoured dinosaur from the Lower Jurassic Kota Formation, Pranhita-Godavari Valley, Andhra Pradesh. J. Geol. Soc. India 59, 575–577 (2002).

    Google Scholar 

  43. de Valais, S., Apesteguía, S. & Udrizar Sauthier, D. Neuvas evidencias de dinosaurios de la Formación Puerto Yeruá (Cretacico), Provincia de Entre Ríos, Argentina. Ameghiniana 40, 631–635 (2003).

    Google Scholar 

  44. Salgado, L. & Gasparini, Z. Reappraisal of an ankylosaurian dinosaur from the Upper Cretaceous of James Ross Island (Antarctica). Geodiversitas 28, 119–135 (2006).

    Google Scholar 

  45. Barrett, P. M. et al. Ankylosaurian dinosaur remains from the Lower Cretaceous of southeastern Australia. Alcheringa 34, 205–217 (2010).

    Article  Google Scholar 

  46. Leahey, L. G. & Salisbury, S. W. First evidence of ankylosaurian dinosaurs (Ornithischia: Thyreophora) from the mid-Cretaceous (late Albian–Cenomanian) Winton Formation of Queensland, Australia. Alcheringa 37, 249–257 (2013).

    Article  Google Scholar 

  47. Galton, P. M. Earliest record of an ankylosaurian dinosaur (Ornithischia: Thyreophora): dermal armour from the Lower Kota Formation (Lower Jurassic) of India. Neues Jahrb. Geol. Palaeontol. Abh. 291, 205–219 (2019).

    Google Scholar 

  48. Carpenter, K., Miles, C. & Cloward, K. Skull of a Jurassic ankylosaur. Nature 393, 782–783 (1998).

    Article  CAS  Google Scholar 

  49. Kirkland, J. I. & Carpenter, K. North America’s first pre-Cretaceous ankylosaur (Dinosauria) from the Upper Jurassic Morrison Formation of western Colorado. BYU Geol. Stud. 40, 25–41 (1994).

    Google Scholar 

  50. Carpenter, K., Miles, C. A., & Cloward, K. in The Armored Dinosaurs (ed. Carpenter, K.) 55–75 (Indiana Univ. Press, 2001).

  51. Galton, P. M. & Carpenter, K. The plated dinosaur Stegosaurus longispinus Gilmore, 1914 (Dinosauria: Ornithischia; Upper Jurassic, western USA), type species of Alcovasaurus n. gen. Neues Jahrb. Geol. Palaeont. Abh. 279, 185–208 (2016).

    Article  Google Scholar 

  52. Mateus, O., Dinis, J. & Cunha, P. P. The Lourinhã Formation: the Upper Jurassic to lowermost Cretaceous of the Lusitanian Basin, Portugal – landscapes where dinosaurs walked. Ciênc. Terra 19, 75–97 (2017).

    Google Scholar 

  53. Sander, P. M. Longbone histology of the Tendaguru sauropods: implications for growth and biology. Paleobiology 26, 466–488 (2000).

    Article  Google Scholar 

  54. Padian, K. & Lamm, E. Bone Histology Of Fossil Tetrapods (Univ. California Press, 2013).

    Book  Google Scholar 

  55. Hayashi, S., Carpenter, K. & Suzuki, D. Different growth patterns between the skeleton and osteoderms of Stegosaurus (Ornithischia: Thyreophora). J. Vertebr. Paleontol. 29, 123–131 (2009).

    Article  Google Scholar 

  56. Stein, M., Hayashi, S. & Sander, P. M. Long bone histology and growth patterns in ankylosaurs: implications for life history and evolution. PLoS ONE 8, e68590 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  57. Waskow, K. & Mateus, O. Dorsal rib histology of dinosaurs and a crocodile from western Portugal: skeletochronological implications on age determination and life history traits. C. R. Palevol 16, 425–439 (2017).

    Article  Google Scholar 

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Acknowledgements

C. Hatch (Natural History Museum) prepared thin sections of the specimen; A. Ball (Natural History Museum) took high-resolution photographs of the slides; B. Creisler (Natural History Museum) advised on etymology. T.M.S. acknowledges support from the Swiss National Science Foundation (grant no. 31003A_179401). We thank the members of the London fossil vertebrates journal club for discussion.

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Authors and Affiliations

  1. Department of Earth Sciences, Natural History Museum, London, UK

    Susannah C. R. Maidment, Emily E. Brown, Vincent Fernandez, Zerina Johanson, Thomas J. Raven & Paul M. Barrett

  2. School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK

    Susannah C. R. Maidment & Emily E. Brown

  3. Department of Earth Sciences, University College London, London, UK

    Sarah J. Strachan

  4. GERA Laboratory, Faculty of Sciences Dhar El Mahraz, SMBA University, Fez, Morocco

    Driss Ouarhache

  5. Palaeontological Institute and Museum, University of Zurich, Zurich, Switzerland

    Torsten M. Scheyer

  6. School of Environment and Technology, University of Brighton, Brighton, UK

    Thomas J. Raven

  7. Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa

    Paul M. Barrett

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Contributions

S.C.R.M. and P.M.B. devised the study. D.O. examined the stratigraphy. S.J.S., T.M.S. and E.E.B. carried out histological analysis. V.F. carried out XCT scanning and analysis. S.C.R.M., P.M.B., D.O., S.J.S., T.M.S., E.E.B., V.F., Z.J. and T.J.R. interpreted the data and wrote the manuscript.

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Correspondence to Susannah C. R. Maidment.

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Peer review information Nature Ecology & Evolution thanks the anonymous reviewers for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Translucent XCT reconstruction of NHMUK PV R37412, Spicomellus afer.

Red shading indicates a grainy cement or fill used to consolidate the specimen. a, lateral and b, dorsal view. Also see Supplementary video.

Extended Data Fig. 2 XCT-scan image of a longitudinal cross-section through NHMUK PV R37412.

White ovals highlight areas where it is possible to see the continuity of cortical and trabecular bone from the spikes to the rod.

Extended Data Fig. 3 The osteoderm and rib parts of the rod were segmented using the following procedure.

a, a section of the specimen was identified for focus; b, longitudinal sections of the specimen were examined in XCT data; c, the boundary between the osteoderm and the rib was identified on longitudinal sections; d, the data were labelled.

Extended Data Fig. 4 Histological thin-section (plane polarized light) showing detail of the spine.

A vascular channel can be observed in the top left of the image. The woven bone matrix of the cortex is dominated by primary osteons. Scattered secondary osteons can be observed in the mid and inner cortex. Large resorption cavities lined with lamellar bone can be observed in the trabecular bone of the core (top right). Red arrows indicate growth (=resting) lines.

Extended Data Fig. 5 Thin section photomicrograph (plane-polarized light) showing detail of the structural fibres in the upper osteodermal part of the rod.

Structural fibre bundles intersect roughly perpendicular to each other. The opaque cast in the top half of the image is probably diagenetic alteration.

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Maidment, S.C.R., Strachan, S.J., Ouarhache, D. et al. Bizarre dermal armour suggests the first African ankylosaur. Nat Ecol Evol 5, 1576–1581 (2021). https://doi.org/10.1038/s41559-021-01553-6

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