Preliminary Study on the Reconstruction and Function of the Hyperelongate Neural Spines in the Dorsal Vertebrae of Deinocheirus mirificus (Theropoda: Ornithomimosauria)
DOI:
https://doi.org/10.62051/5p1vfv02Keywords:
Mesozoic; Dinosauria; Functional morphology; Osteology; Sail-Backed.Abstract
Deinocheirus is a bizarre and unique theropod dinosaur. The holotype of Deinocheirus was discovered in 1976, but its characteristics and phylogenetic position remained largely enigmatic due to the scarcity of fossil material. This changed in 2014 when Lee et al. described two additional specimens, providing a deeper insight into this mysterious creature. Notably, the smaller specimen MPC-D 100/128 preserved a relatively complete dorsal vertebra with hyperelongated neural spines, reaching up to 8.5 times the height of the corresponding centra. This suggests that Deinocheirus possessed a raised dorsal sail or hump-like structure. Elongated neural spines have evolved multiple times in dinosaurs, including in ornithopods of ornithischians as well as theropods and sauropods of saurischians, with various hypothesized functions such as thermoregulation, fat storage, or sexual display. However, previous research on the neural spines of Deinocheirus has been limited to brief description, lacking detailed analysis and leaving the morphology and function of these dorsal structures poorly understood. To better understand the possible dorsal structure of Deinocheirus and its ecological role, this study examines the dorsal neural spines of Deinocheirus and 26 other dinosaurs. Through measurement and comparative analyses, we categorize the height and width of neural spines into different categories. Our comparison reveal that the neural spines of Deinocheirus are most similar to those of Spinosaurus and Ouranosaurus, with a height ratios exceeding 7 and overall morphology closer to the latter. Additionally, the anteroposterior width of neural spines of Deinocheirus is slightly narrower than that of Spinosaurus and Ouranosaurus. Based on these data and previous studies, we infer that the hyperelongated neural spines of Deinocheirus may serve dual functions: supporting a sail related to aquatic habits and a hump associated with an intricate interspinous ligament system, potentially for fat storage to aid in surviving dry seasons. Finally, we discuss avenues for future research, such as bone histology and finite element analysis, which could provide further insights into the morphology and function of the neural spines of Deinocheirus.
Downloads
References
[1] Allain, R., Xaisanavong, T., Richir, P., & Khentavong, B. (2012). The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the Early Cretaceous of Laos. Die Naturwissenschaften, 99(5), 369–377.
[2] Agliano, A., Sander, P. M., & Wintrich, T. (2021). Bone histology and microanatomy of Edaphosaurus and Dimetrodon (Amniota, Synapsida) vertebrae from the Lower Permian of Texas. The Anatomical Record, 304(3), 570-583.
[3] Brink, K. S., MacDougall, M. J., & Reisz, R. R. (2019). Dimetrodon (Synapsida: Sphenacodontidae) from the cave system at Richards Spur, OK, USA, and a comparison of Early Permian-aged vertebrate paleoassemblages. Die Naturwissenschaften, 106(1-2), 2.
[4] Bailey, J.B. (1997). Neural spine elongation in dinosaurs: sailbacks or buffalo-backs? Journal of Paleontology, 71, 1124 - 1146.
[5] Bell, P. R., Currie, P. J., & Lee, Y. N. (2012). Tyrannosaur feeding traces on Deinocheirus (Theropoda:? Ornithomimosauria) remains from the Nemegt Formation (Late Cretaceous), Mongolia. Cretaceous Research, 37, 186-190.
[6] Bertozzo, F., Dalla Vecchia, F. M., & Fabbri, M. (2017). The Venice specimen of Ouranosaurus nigeriensis (Dinosauria, Ornithopoda). PeerJ, 5, e3403.
[7] Blows, W. T., & Honeysett, K. (2014). First Valanginian Polacanthus foxii (Dinosauria, Ankylosauria) from England, from the Lower Cretaceous of Bexhill, Sussex. Proceedings of the Geologists' Association, 125(2), 233-251.
[8] Bramwell, C. D., Fellgett, P.P. (1973) Thermal regulation in sail lizards. Nature. 242: 203–205
[9] Brochu, C. A. (2003). Osteology of Tyrannosaurus Rex: Insights from a nearly complete Skeleton and High-Resolution Computed Tomographic Analysis of the Skull. Journal of Vertebrate Paleontology, 22(sup4), 1–138
[10] Cerda, I. A., Novas, F. E., Carballido, J. L., & Salgado, L. (2022). Osteohistology of the hyperelongate hemispinous processes of Amargasaurus cazaui (Dinosauria: Sauropoda): Implications for soft tissue reconstruction and functional significance. Journal of Anatomy, 240(6), 1005-1019.
[11] D'Emic, M. D., Melstrom, K. M., & Eddy, D. R. (2012). Paleobiology and geographic range of the large-bodied Cretaceous theropod dinosaur Acrocanthosaurus atokensis. Palaeogeography, Palaeoclimatology, Palaeoecology, 333-334, 13-23.
[12] Dodson, P. (1975). Taxonomic Implications of Relative growth in Lambeosaurine Hadrosaurs. Systematic Biology, 24, 37-54.
[13] Gignac, P.M., & Erickson, G.M. (2017). The Biomechanics Behind Extreme Osteophagy in Tyrannosaurus rex. Scientific Reports, 7.
[14] Gallina, P. A., Apesteguía, S., Canale, J. I., & Haluza, A. (2019). A new long-spined dinosaur from Patagonia sheds light on sauropod defense system. Scientific Reports, 9(1), 1392.
[15] Gasulla, J.M., Escaso, F., Narváez, I., Ortega, F., & Sanz, J.L. (2015). A New Sail-Backed Styracosternan (Dinosauria: Ornithopoda) from the Early Cretaceous of Morella, Spain. PLoS ONE, 10.
[16] Gianechini, F. A., Makovicky, P. J., Apesteguía, S., & Cerda, I. (2018). Postcranial skeletal anatomy of the holotype and referred specimens of Buitreraptor gonzalezorum Makovicky, Apesteguía and Agnolín 2005 (Theropoda, Dromaeosauridae), from the Late Cretaceous of Patagonia. PeerJ, 6, e4558.
[17] Harris, J. D. (1998). A Reanalysis of Acrocanthosaurus atokensis, its Phylogenetic Status, and Paleobiogeographic Implications, Based on a New Specimen from Texas: Bulletin 13 (Vol. 13). New Mexico Museum of Natural History and Science.
[18] Hedrick, B. P., Zanno, L. E., Wolfe, D. G., & Dodson, P. (2015). The Slothful Claw: Osteology and Taphonomy of Nothronychus mckinleyi and N. graffami (Dinosauria: Theropoda) and Anatomical Considerations for Derived Therizinosaurids. PloS one, 10(6), e0129449.
[19] Huttenlocker, A. K., Rega, E., & Sumida, S. S. (2010). Comparative anatomy and osteohistology of hyperelongate neural spines in the sphenacodontids Sphenacodon and Dimetrodon (Amniota: Synapsida). Journal of morphology, 271(12), 1407–1421.
[20] Ibrahim, N., Sereno, P.C., Dal Sasso, C., Maganuco, S., Fabbri, M., Martill, D.M., Zouhri, S., Myhrvold, N.P., & Iurino, D.A. (2014). Semiaquatic adaptations in a giant predatory dinosaur. Science, 345, 1613 - 1616.
[21] Jerzykiewicz, T., & Russell, D.A. (1991). Late Mesozoic stratigraphy and vertebrates of the Gobi Basin. Cretaceous Research, 12, 345-377.
[22] Karikehalli, S. (2019, January 17). Watch a black heron fool fish by turning into an umbrella. Retrieved from https://www.audubon.org/news/watch-black-heron-fool-fish-turning-umbrella
[23] Ibrahim N, Sereno PC, Varricchio DJ, Martill DM, Dutheil DB, Unwin DM, Baidder L, Larsson HCE, Zouhri S, Kaoukaya A. Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco. Zookeys. 2020 Apr 21;928:1-216. doi: 10.3897/zookeys.928.47517. PMID: 32362741; PMCID: PMC7188693.
[24] Ibrahim, N., Maganuco, S., Dal Sasso, C. et al. Tail-propelled aquatic locomotion in a theropod dinosaur. Nature 581, 67–70 (2020). https://doi.org/10.1038/s41586-020-2190-3
[25] Mazzetta, G. V., Cisilino, A. P., Blanco, R. E., & Calvo, N. (2009). Cranial mechanics and functional interpretation of the horned carnivorous dinosaur Carnotaurus sastrei. Journal of Vertebrate Paleontology, 29(3), 822-830.
[26] Lautenschlager, S. (2014). Morphological and functional diversity in therizinosaur claws and the implications for theropod claw evolution. Proceedings of the Royal Society B: Biological Sciences, 281(1785), 20140497.
[27] Lee, Y., Barsbold, R., Currie, P.J., Kobayashi, Y., Lee, H., Godefroit, P., Escuillié, F., & Chinzorig, T. (2014). Resolving the long-standing enigmas of a giant ornithomimosaur Deinocheirus mirificus. Nature, 515, 257-260.
[28] Leonardo & José F. Bonaparte. 1991. Un nuevo sauropodo Dicraeosauridae, Amargasaurus cazaui gen. et sp. nov. de la Formación La Amarga, Neocomiano de la Provincia del Neuquén, Argentina. Ameghiniana 28(3-4): 333-346.
[29] Maidment, S. C. R., Norman, D. B., Barrett, P. M., & Upchurch, P. (2008). Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia). Journal of Systematic Palaeontology, 6(4), 367–407.
[30] Naish D (2011) Theropod dinosaurs. In: Batten DJ (ed) English wealden fossils. The Palaeontological Association, London, pp 526–559
[31] Osmo´lska, H. & Roniewicz, E. Deinocheiridae, a new family of theropod dinosaurs.Palaeontol. Polonica 21, 5–19 (1970).
[32] O’Connor, P. M. (2007). THE POSTCRANIAL AXIAL SKELETON OF MAJUNGASAURUS CRENATISSIMUS (THEROPODA: ABELISAURIDAE) FROM THE LATE CRETACEOUS OF MADAGASCAR. Journal of Vertebrate Paleontology, 27(sup2), 127–163
[33] Ortega, F., Escaso, F., & Sanz, J. L. (2010). A bizarre, humped Carcharodontosauria (Theropoda) from the Lower Cretaceous of Spain. Nature, 467(7312), 203-206
[34] Qin, Z., Liao, C. C., Benton, M. J., & Rayfield, E. J. (2023). Functional space analyses reveal the function and evolution of the most bizarre theropod manual unguals. Communications biology, 6(1), 181.
[35] Remes, K., Ortega, F., Fierro, I., Joger, U., Kosma, R., Ferrer, J. M., Project PALDES, Niger Project SNHM, Ide, O. A., & Maga, A. (2009). A new basal sauropod dinosaur from the middle Jurassic of Niger and the early evolution of sauropoda. PloS one, 4(9), e6924.
[36] Rayfield E. J. (2005). Using finite-element analysis to investigate suture morphology: a case study using large carnivorous dinosaurs. The anatomical record. Part A, Discoveries in molecular, cellular, and evolutionary biology, 283(2), 349–365. https://doi.org/10.1002/ar.a.20168Vidal, D., Mocho, P., Aberasturi, A., Sanz, J. L., & Ortega, F. (2020). High browsing skeletal adaptations in Spinophorosaurus reveal an evolutionary innovation in sauropod dinosaurs. Scientific reports, 10(1), 6638.
[37] Watanabe, A., Eugenia Leone Gold, M., Brusatte, S. L., Benson, R. B., Choiniere, J., Davidson, A., & Norell, M. A. (2015). Vertebral Pneumaticity in the Ornithomimosaur Archaeornithomimus (Dinosauria: Theropoda) Revealed by Computed Tomography Imaging and Reappraisal of Axial Pneumaticity in Ornithomimosauria. PloS one, 10(12), e0145168.
[38] Wedel, M.J. (2008). Lightening the giants: pneumatic bones in sauropod dinosaurs and their implications for mass estimates.
[39] Wilson, J. P., Woodruff, D. C., Gardner, J. D., Flora, H. M., Horner, J. R., & Organ, C. L. (2016). Vertebral Adaptations to Large Body Size in Theropod Dinosaurs. PloS one, 11(7), e0158962.
[40] Wilson, J. A. (2012). New vertebral laminae and patterns of serial variation in vertebral laminae of sauropod dinosaurs. Paleontological Society Papers, 32(7). Museum of Paleontology, The University of Michigan.
[41] Wilson, J. A., & Allain, R. (2015). Osteology of Rebbachisaurus garasbae Lavocat, 1954, a diplodocoid (Dinosauria, Sauropoda) from the early Late Cretaceous–aged Kem Kem beds of southeastern Morocco. Journal of Vertebrate Paleontology, 35(4).
[42] Windholz, G. J., & Cerda, I. A. (n.d.). Paleohistology of two dicraeosaurid dinosaurs (Sauropoda; Diplodocoidea) from La Amarga Formation (Barremian-Aptian, Lower Cretaceous), Neuquén Basin, Argentina: Paleobiological implications. Universidad Nacional de Río Negro, Instituto de Investigación en Paleobiología y Geología, Río Negro, Argentina.
[43] Xu, X., Upchurch, P., Mannion, P. D., Barrett, P. M., Regalado-Fernandez, O. R., Mo, J., Ma, J., & Liu, H. (2018). A new Middle Jurassic diplodocoid suggests an earlier dispersal and diversification of sauropod dinosaurs. Nature communications, 9(1), 2700.
Downloads
Published
Conference Proceedings Volume
Section
License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.