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Lot Essay
The preserved fossil elements comprise four diagnostic osteological areas, which are necessary for an identification of the hitherto undescribed specimen: the mandible, the hands, the hind limbs, and the pelvic girdle. The bones are remarkably well preserved in three dimensions, showing minimal compaction.
The skeleton is exceptionally complete among other known specimens of the Caenagnathidae family, of which this is certainly a member. Worldwide, only one other known caenagnathid specimen preserves almost the same elements of the skeleton.
Spike was discovered during an excavation on private land in 2022 in northwestern South Dakota, USA. It was unearthed from a cliff formed by the Late Cretaceous deposits of the Hell Creek Formation, which is recognised worldwide for its wealth of dinosaur fossils. However, remains of caenagnathids from there and, more generally, from North America, are exceedingly rare.
From the Hell Creek Formation, only two caenagnathid species are described: Anzu wyliei and Eoneophron infernalis. Four partial skeletons of Anzu wyliei, which reached a length of more than 3.5 metres, allowed for the reconstruction of the species to about 80%. The smaller Eoneophron infernalis is known from a nearly complete hind limb skeleton only, the bones of which are heavily compacted. A preliminary comparison of Spike with these two described species shows that Spike has distinct features that could possibly belong to a new species.
Spike’s original bones consist of seven of the posterior-most cervical and nine caudal vertebrae, three basal chevrons, a complete left ulna, eight thoracic ribs, partial gastral elements, a nearly complete pelvic girdle – including the sacral vertebrae, with only the left ischium missing – the ulna and third metacarpal of the left arm, metacarpal one and four digital bones of the right hand, a complete right hind limb (of which only the basal phalanx of digit one is missing), and a partial left foot comprising all metatarsals and some digital bones. The specimen also comprises a bone fragment of the right jugal area, a large, diagnostic fragment of the mandible, and a supposed element of the dorsal cranial crest. The rest of the skeleton has been professionally restored by mirroring the preserved contralateral bone elements and by comparison with closely related species using the proportions of Spike’s original bones.
Caenagnathids – the ‘Modern Jaws’
Caenagnathid were ratite-like theropods that belong to Oviraptorosauria and roamed this planet throughout the late Cretaceous (around 80 to 66 million years ago).Remains of this enigmatic dinosaur group have been reported from Asia and North America. Currently, about 17 species of Caenagnathidae have been described, mostly based on fragmentary skeletons or isolated bones.
With their edentulous beaks, long necks, short tails, long and powerful hind limbs, and their plumage, caenagnathids have the appearance of ratite birds with slightly curved beaks. Their domed skull superficially resembles a cassowary. Their arms ended in hands with long, flexible fingers that enabled the animals to manipulate food. With their edentulous sharp beak, they could handle any type of prey including vegetation – namely nutrient-rich angiosperm fruits – carcasses, eggs and small animals of all kinds.
The first caenagnathid theropod, Caenagnathus collinsi, was discovered in the year 1936 in the Steveville, Alberta, Canada, by the Canadian field-naturalist Raymond Martin Sternberg, son of the famous Canadian palaeontologist Charles M. Sternberg. Raymond presented his discovery to his father and an experienced ornithologist, Dr Alexander Wetmore, at that time assistant secretary of the Smithsonian Institution, Washington D.C. Among some postcranial elements, Raymond’s discovery comprised a complete edentulous mandible that was strikingly similar to that of extant ostrich-like birds. Charles Sternberg and Wetmore encouraged Raymond to publish his enigmatic discovery. In January 1940, Raymond Sternberg’s description of ‘[a] toothless bird from the Cretaceous of Alberta’ was published in the recognized Journal of Paleontology. Surprised by the discovery of a bird with ‘modern’ jaws that lived during the Late Cretaceous, he christened his finding Caenagnathus, ‘modern jaw’. It was not until the early seventies, when palaeontologists recognised that Caenagnathus in fact belonged to a group of theropod dinosaurs, the Oviraptorosauria, that had evolved edentulous beaks convergent to birds.
Oviraptorosauria – from egg thieves to caring parents
Oviraptorosauria are distant cousins of dromaeosaurs such as Velociraptor or Deinonychus. Because of the long-fingered manipulative hands, this type of theropods is referred to as Maniraptoria, the ‘hand snatchers’.
The first oviraptorosaurid was discovered in 1923 during an expedition led by the famous American adventurer, explorer, and naturalist Roy Chapman Andrews in the Late Cretaceous deposits of the Djadoktha Formation near the famous Flaming Cliffs in Mongolia. The specimen was found over a nest with elongate eggs that were related to the primitive ceratopsian Protoceratops. That specimen comprises a badly preserved partial skeleton lacking its hind portion. The bones, including the skull, are heavily crushed. The specimen was handed over to the palaeontologist Henry Fairfield Osborne, who published the edentulous theropod in the year 1924 as Oviraptor philoceratops, the egg seizer with a fondness for ceratopsians, thereby putting the eggs and the edentulous beak as a cracking device together.
It was not until 1994 when the mystery of the supposed Protoceratos eggs was understood. The elongate eggs did not at all contain Protoceratops embryos, but rather those of oviraptorosaurids. In the year 1995, the American palaeontologist Mark Norell and coauthors clarified the finding. They described a specimen of the large oviraptorosaurid Citipati osmolskae sitting on its nest full of elongate eggs in an apparent breeding position. The specimen was nicknamed ‘Big Mama’. The egg seizers have mutated to caring parents – but kept their name.
Oviraptorosaurids ranged in mass from 5 kilograms turkey-sized sprinters, like the gracile Caudipteryx zoui to 1.5 to 2 metric ton monsters like Gigantoraptor erlianensis, and Beibeilong sinensis, both members of Caenagnathidae. While the earliest oviraptorosaurids possessed a few teeth in the tip of their beaks, the later species were edentulous with short, stout beaks. Whether they were carnivorous or herbivorous is still under debate, but today it is assumed that they were predominantly omnivorous.
Late Cretaceous oviraptorosaurs are divided into two major groups: Oviraptoridae exclusively inhabiting Asia and Caenagnathidae coming from both Asia and North America. Although the fossil record of oviraptorosaurs is among the best of any theropod dinosaurs, it is heavily biased towards the oviraptorids. By contrast, caenagnathids are very poorly known, and are among the rarest fossils in the deposits where they are found. For this reason, skeletons that preserve numerous bones, especially those of the jaws, hands, and feet, are vital in illuminating the still-debated taxonomy and ecology of caenagnathids.
Spike’s outstanding preservation and restoration
The postcranial bones of Spike are preserved in three dimensions, with minimal compaction cracks. The proportions of the bones in this specimen provide evidence that they come from a single individual. Many bones, including phalanxes and vertebrae, are highly complete. Partially preserved bone groups are reconstructed via sculpting or 3D printing to ensure that they are as close as possible to anatomical accuracy, especially where paired bones could be duplicated. Thus, as far as we are aware, Spike represents one of the most accurate skeletal reconstructions of a caenagnathid theropod with properly restored proportions to date, especially given the dearth of comparably articulated known skeletons.
Important regions of Spike’s anatomy are represented by at least one element, which is exceptional among known specimens of caenagnathids. Some 100 bones out of approximately 320 are identified. It is important to note that the bulk of known caenagnathid specimens comprise less than 10% of the skeleton. Consequently, Spike exhibits an important degree of completeness.
The reconstruction of the fragmentary skull is based on the osteology of more complete skulls of Mongolian caenagnathids, including that of Citipati osmolskae. The height of the crest is therefore speculative, and is constructed within the plausible range based on what is known about caenagnathid skulls. The skull of Spike contains a pair of nasal bones with an unusual morphology, which differs from the nasal bones known from other oviraptorosaurids. The identification of these bones related to the nasal area, as well as that of the jugal, may have an impact on the overall morphology of Spike’s skull and would make for potentially groundbreaking further study into this group of dinosaurs.
The missing elements of the mandible are restored based on similarly sized mandibles of other caenagnathids, but the diagnostic area of the bone, namely its anterior half, is superbly preserved and an essential diagnostic element. Additionally, due to its intrinsic stability, this element is preserved in other caenagnathids as well. Based on comparisons to date, the rostral part of the mandible of Spike does not match those of other known North American caenagnathids.
Was Spike feathered?
Because no trace of soft tissue was aligned with Spike’s remnants, there is no direct evidence that Spike was indeed feathered. The possibility of the presence of feathers is hinted at by structures on the back of the left ulna that resemble quill knobs. Such knobs are known from numerous oviraptotosaurids.
How old was Spike?
In dinosaurs and crocodilians, the fusion status of the suture between neural arch and vertebral body, the so-called neurocentral suture, is one of the features that is indicative for the individual ontogenetic stage of these animals. In the vertebral column of Spike, all neurocentral sutures of the neck, trunk and tail vertebrae, which are sufficiently well preserved, are fused but still superficially visible as an engraved line. This is contradicted by the fact that only two sacral vertebrae of Spike are fused instead of six or more in other caenagnathids. Still, it appears very likely that Spike was a late subadult individual and thus almost fully adult. The unfused sacral vertebrae were mechanically stabilised between the pelvic plates and thus may have had a delayed fusion.
Conclusion
The specimen represents a remarkably complete skeleton of the extremely rare dinosaur group Caenagnathidae. Typically, caenagnathids are known only from fragmentary remains, making this specimen exceptional. It is remarkable for its high quality of preservation and the inclusion of bones from each of the four diagnostic regions of the caenagnathid skeleton: the skull, hands, pelvis, and feet. Only one other published caenagnathid specimen preserves all these regions, but in the present specimen, the pelvis and feet appear to be in much better condition. Together, these factors give the specimen scientific significance; and the expertly prepared mount makes for a visually striking dinosaur.
Christie’s would like to thank Professor Eberhard Frey for his assistance preparing this catalogue note.
COMPARATIVE LITERATURE
Atkins-Weltman, K. L., D. J. Simon, H. N. Woodward, G. F. Funston, and E. Snively. “A New Oviraptorosaur (Dinosauria: Theropoda) from the End-Maastrichtian Hell Creek Formation of North America.” PLOS ONE 19, no. 1 (2024): e0294901.
Balanoff, A. M., and M. A. Norell. “Osteology of Khaan mckennai (Oviraptorosauria: Theropoda).” Bulletin of the American Museum of Natural History 372 (2012): 1–77.
Brochu, C. A. “Closure of Neurocentral Sutures during Crocodilian Ontogeny: Implications for Maturity Assessment in Fossil Archosaurs.” Journal of Vertebrate Paleontology 16, no. 1 (1996): 49–62.
Clark, J. M., M. A. Norell, and T. Rowe. “Cranial Anatomy of Citipati osmolskae (Theropoda, Oviraptorosauria), and a Reinterpretation of the Holotype of Oviraptor philoceratops.” American Museum Novitates (2002): 1–24.
Coombs, W. P. “Modern Analogs for Dinosaur Nesting and Parental Behavior.” In Paleobiology of the Dinosaurs, edited by J. O. Farlow, 21–54. Geological Society of America Special Paper 238. Boulder: Geological Society of America, 1989.
Cracraft, J. “Caenagnathiformes: Cretaceous Birds Convergent in Jaw Mechanism to Dicynodont Reptiles.” Journal of Paleontology 45 (1971): 805–809.
Fawcett, K. “Scientists Discover a Large and Feathered Dinosaur That Once Roamed North America.” Smithsonian Magazine, March 20, 2014.
Funston, G. F. Anatomy, Systematics, and Evolution of Oviraptorosauria (Dinosauria, Theropoda). PhD diss., University of Alberta, 2019.
Funston, G. F. “Caenagnathids of the Dinosaur Park Formation (Campanian) of Alberta, Canada: Anatomy, Osteohistology, Taxonomy, and Evolution.” Vertebrate Anatomy Morphology Palaeontology 8 (2020): 105–153.
Funston, G. F., and P. J. Currie. “A New Caenagnathid (Dinosauria: Oviraptorosauria) from the Horseshoe Canyon Formation of Alberta, Canada, and a Reevaluation of the Relationships of Caenagnathidae.” Journal of Vertebrate Paleontology 36 (2016): e1160910.
Funston, G. F. “Osteology of the Two-Fingered Oviraptorid Oksoko avarsan (Theropoda: Oviraptorosauria).” Zoological Journal of the Linnean Society (2024): zlae011.
Funston, G. F., S. E. Mendonça, P. J. Currie, and R. Barsbold. “Oviraptorosaur Anatomy, Diversity and Ecology in the Nemegt Basin.” Palaeogeography, Palaeoclimatology, Palaeoecology 494 (2018): 101–120.
Hendrickx, C., S. A. Hartman, and O. Mateus. “An Overview of Non-Avian Theropod Discoveries and Classification.” PalArch’s Journal of Vertebrate Palaeontology 12, no. 1 (2015): 1–73.
Hone, D. W. E., A. A. Farke, and M. J. Wedel. “Ontogeny and the Fossil Record: What, If Anything, Is an Adult Dinosaur?” Biology Letters 12, no. 2 (2016): 20150947.
Ikejiri, T. “Sequence of Closure of Neurocentral Sutures in Camarasaurus (Sauropoda) and Implications for Phylogeny in Reptilia.” Journal of Vertebrate Paleontology 23, no. 3 (Suppl.) (2003): 65A.
Ji, Q., P. J. Currie, M. A. Norell, and S. Ji. “Two Feathered Dinosaurs from Northeastern China.” Nature 393, no. 6687 (1998): 753–761.
Lamanna, M. C., H. D. Sues, E. R. Schachner, and T. R. Lyson. “A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America.” PLOS ONE 9, no. 3 (2015): e92022.
Meade, L. E., and W. Ma. “Cranial Muscle Reconstructions Quantify Adaptation for High Bite Forces in Oviraptorosauria.” Scientific Reports 12, no. 1 (2022): 3010.
Norell, M. A., J. M. Clark, L. M. Chiappe, and D. Dashzeveg. “A Nesting Dinosaur.” Nature 378, no. 6559 (1995).
Norell, M. A., J. M. Clark, D. Dashzeveg, R. Barsbold, L. M. Chiappe, A. R. Davidson, M. C. McKenna, P. Altangerel, and M. J.
Novacek. “A Theropod Dinosaur Embryo and the Affinities of the Flaming Cliffs Dinosaur Eggs.” Science 266, no. 5186 (1994): 779–782.
Osborn, H. F. “Three New Theropoda, Protoceratops Zone, Central Mongolia.” American Museum Novitates 144 (1924): 1–12.
Osmólska, H., P. J. Currie, and R. Barsbold. “Oviraptorosauria.” In The Dinosauria, edited by D. B. Weishampel, P. Dodson, and H. Osmólska, 165–183. Berkeley: University of California Press, 2004.
Pu, H., D. K. Zelenitsky, J. Lü, P. J. Currie, K. Carpenter, L. Xu, E. B. Koppelhus, S. Jia, L. Xiao, H. Chuang, T. Li, M. Kundrát, and C. Shen. “Perinate and Eggs of a Giant Caenagnathid Dinosaur from the Late Cretaceous of Central China.” Nature Communications 8 (2017): 14952.
Senter, P., and J. M. Parrish. “Functional Analysis of the Hands of the Theropod Dinosaur Chirostenotes pergracilis: Evidence for an Unusual Paleoecological Role.” PaleoBios 25, no. 2 (2005): 9–19.
Sternberg, R. M. “A Toothless Bird from the Cretaceous of Alberta.” Journal of Paleontology 14, no. 1 (1940): 81–85.
Thulborn, R. A. “Nest of the Dinosaur Protoceratops.” Lethaia 25, no. 2 (1992): 145–149.
Turner, A. H., D. Pol, J. A. Clarke, G. M. Erickson, and M. A. Norell. “A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight.” Science 317, no. 5843 (2007): 1378–1381.
Xing, X., Q. Tan, J. Wang, X. Zhao, and L. Tan. “A Gigantic Bird-like Dinosaur from the Late Cretaceous of China.” Nature 447, no. 7146 (2007): 844–847.
Xu, X., Y.-N. Cheng, X.-L. Wang, and C.-H. Chang. “An Unusual Oviraptorosaurian Dinosaur from China.” Nature 419, no. 6904 (2002): 291–293.
Zelenitsky, D. K., F. Therrien, G. M. Erickson, and C. De Buhr. “Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins.” Science 338 (2012): 510–514.
The skeleton is exceptionally complete among other known specimens of the Caenagnathidae family, of which this is certainly a member. Worldwide, only one other known caenagnathid specimen preserves almost the same elements of the skeleton.
Spike was discovered during an excavation on private land in 2022 in northwestern South Dakota, USA. It was unearthed from a cliff formed by the Late Cretaceous deposits of the Hell Creek Formation, which is recognised worldwide for its wealth of dinosaur fossils. However, remains of caenagnathids from there and, more generally, from North America, are exceedingly rare.
From the Hell Creek Formation, only two caenagnathid species are described: Anzu wyliei and Eoneophron infernalis. Four partial skeletons of Anzu wyliei, which reached a length of more than 3.5 metres, allowed for the reconstruction of the species to about 80%. The smaller Eoneophron infernalis is known from a nearly complete hind limb skeleton only, the bones of which are heavily compacted. A preliminary comparison of Spike with these two described species shows that Spike has distinct features that could possibly belong to a new species.
Spike’s original bones consist of seven of the posterior-most cervical and nine caudal vertebrae, three basal chevrons, a complete left ulna, eight thoracic ribs, partial gastral elements, a nearly complete pelvic girdle – including the sacral vertebrae, with only the left ischium missing – the ulna and third metacarpal of the left arm, metacarpal one and four digital bones of the right hand, a complete right hind limb (of which only the basal phalanx of digit one is missing), and a partial left foot comprising all metatarsals and some digital bones. The specimen also comprises a bone fragment of the right jugal area, a large, diagnostic fragment of the mandible, and a supposed element of the dorsal cranial crest. The rest of the skeleton has been professionally restored by mirroring the preserved contralateral bone elements and by comparison with closely related species using the proportions of Spike’s original bones.
Caenagnathids – the ‘Modern Jaws’
Caenagnathid were ratite-like theropods that belong to Oviraptorosauria and roamed this planet throughout the late Cretaceous (around 80 to 66 million years ago).Remains of this enigmatic dinosaur group have been reported from Asia and North America. Currently, about 17 species of Caenagnathidae have been described, mostly based on fragmentary skeletons or isolated bones.
With their edentulous beaks, long necks, short tails, long and powerful hind limbs, and their plumage, caenagnathids have the appearance of ratite birds with slightly curved beaks. Their domed skull superficially resembles a cassowary. Their arms ended in hands with long, flexible fingers that enabled the animals to manipulate food. With their edentulous sharp beak, they could handle any type of prey including vegetation – namely nutrient-rich angiosperm fruits – carcasses, eggs and small animals of all kinds.
The first caenagnathid theropod, Caenagnathus collinsi, was discovered in the year 1936 in the Steveville, Alberta, Canada, by the Canadian field-naturalist Raymond Martin Sternberg, son of the famous Canadian palaeontologist Charles M. Sternberg. Raymond presented his discovery to his father and an experienced ornithologist, Dr Alexander Wetmore, at that time assistant secretary of the Smithsonian Institution, Washington D.C. Among some postcranial elements, Raymond’s discovery comprised a complete edentulous mandible that was strikingly similar to that of extant ostrich-like birds. Charles Sternberg and Wetmore encouraged Raymond to publish his enigmatic discovery. In January 1940, Raymond Sternberg’s description of ‘[a] toothless bird from the Cretaceous of Alberta’ was published in the recognized Journal of Paleontology. Surprised by the discovery of a bird with ‘modern’ jaws that lived during the Late Cretaceous, he christened his finding Caenagnathus, ‘modern jaw’. It was not until the early seventies, when palaeontologists recognised that Caenagnathus in fact belonged to a group of theropod dinosaurs, the Oviraptorosauria, that had evolved edentulous beaks convergent to birds.
Oviraptorosauria – from egg thieves to caring parents
Oviraptorosauria are distant cousins of dromaeosaurs such as Velociraptor or Deinonychus. Because of the long-fingered manipulative hands, this type of theropods is referred to as Maniraptoria, the ‘hand snatchers’.
The first oviraptorosaurid was discovered in 1923 during an expedition led by the famous American adventurer, explorer, and naturalist Roy Chapman Andrews in the Late Cretaceous deposits of the Djadoktha Formation near the famous Flaming Cliffs in Mongolia. The specimen was found over a nest with elongate eggs that were related to the primitive ceratopsian Protoceratops. That specimen comprises a badly preserved partial skeleton lacking its hind portion. The bones, including the skull, are heavily crushed. The specimen was handed over to the palaeontologist Henry Fairfield Osborne, who published the edentulous theropod in the year 1924 as Oviraptor philoceratops, the egg seizer with a fondness for ceratopsians, thereby putting the eggs and the edentulous beak as a cracking device together.
It was not until 1994 when the mystery of the supposed Protoceratos eggs was understood. The elongate eggs did not at all contain Protoceratops embryos, but rather those of oviraptorosaurids. In the year 1995, the American palaeontologist Mark Norell and coauthors clarified the finding. They described a specimen of the large oviraptorosaurid Citipati osmolskae sitting on its nest full of elongate eggs in an apparent breeding position. The specimen was nicknamed ‘Big Mama’. The egg seizers have mutated to caring parents – but kept their name.
Oviraptorosaurids ranged in mass from 5 kilograms turkey-sized sprinters, like the gracile Caudipteryx zoui to 1.5 to 2 metric ton monsters like Gigantoraptor erlianensis, and Beibeilong sinensis, both members of Caenagnathidae. While the earliest oviraptorosaurids possessed a few teeth in the tip of their beaks, the later species were edentulous with short, stout beaks. Whether they were carnivorous or herbivorous is still under debate, but today it is assumed that they were predominantly omnivorous.
Late Cretaceous oviraptorosaurs are divided into two major groups: Oviraptoridae exclusively inhabiting Asia and Caenagnathidae coming from both Asia and North America. Although the fossil record of oviraptorosaurs is among the best of any theropod dinosaurs, it is heavily biased towards the oviraptorids. By contrast, caenagnathids are very poorly known, and are among the rarest fossils in the deposits where they are found. For this reason, skeletons that preserve numerous bones, especially those of the jaws, hands, and feet, are vital in illuminating the still-debated taxonomy and ecology of caenagnathids.
Spike’s outstanding preservation and restoration
The postcranial bones of Spike are preserved in three dimensions, with minimal compaction cracks. The proportions of the bones in this specimen provide evidence that they come from a single individual. Many bones, including phalanxes and vertebrae, are highly complete. Partially preserved bone groups are reconstructed via sculpting or 3D printing to ensure that they are as close as possible to anatomical accuracy, especially where paired bones could be duplicated. Thus, as far as we are aware, Spike represents one of the most accurate skeletal reconstructions of a caenagnathid theropod with properly restored proportions to date, especially given the dearth of comparably articulated known skeletons.
Important regions of Spike’s anatomy are represented by at least one element, which is exceptional among known specimens of caenagnathids. Some 100 bones out of approximately 320 are identified. It is important to note that the bulk of known caenagnathid specimens comprise less than 10% of the skeleton. Consequently, Spike exhibits an important degree of completeness.
The reconstruction of the fragmentary skull is based on the osteology of more complete skulls of Mongolian caenagnathids, including that of Citipati osmolskae. The height of the crest is therefore speculative, and is constructed within the plausible range based on what is known about caenagnathid skulls. The skull of Spike contains a pair of nasal bones with an unusual morphology, which differs from the nasal bones known from other oviraptorosaurids. The identification of these bones related to the nasal area, as well as that of the jugal, may have an impact on the overall morphology of Spike’s skull and would make for potentially groundbreaking further study into this group of dinosaurs.
The missing elements of the mandible are restored based on similarly sized mandibles of other caenagnathids, but the diagnostic area of the bone, namely its anterior half, is superbly preserved and an essential diagnostic element. Additionally, due to its intrinsic stability, this element is preserved in other caenagnathids as well. Based on comparisons to date, the rostral part of the mandible of Spike does not match those of other known North American caenagnathids.
Was Spike feathered?
Because no trace of soft tissue was aligned with Spike’s remnants, there is no direct evidence that Spike was indeed feathered. The possibility of the presence of feathers is hinted at by structures on the back of the left ulna that resemble quill knobs. Such knobs are known from numerous oviraptotosaurids.
How old was Spike?
In dinosaurs and crocodilians, the fusion status of the suture between neural arch and vertebral body, the so-called neurocentral suture, is one of the features that is indicative for the individual ontogenetic stage of these animals. In the vertebral column of Spike, all neurocentral sutures of the neck, trunk and tail vertebrae, which are sufficiently well preserved, are fused but still superficially visible as an engraved line. This is contradicted by the fact that only two sacral vertebrae of Spike are fused instead of six or more in other caenagnathids. Still, it appears very likely that Spike was a late subadult individual and thus almost fully adult. The unfused sacral vertebrae were mechanically stabilised between the pelvic plates and thus may have had a delayed fusion.
Conclusion
The specimen represents a remarkably complete skeleton of the extremely rare dinosaur group Caenagnathidae. Typically, caenagnathids are known only from fragmentary remains, making this specimen exceptional. It is remarkable for its high quality of preservation and the inclusion of bones from each of the four diagnostic regions of the caenagnathid skeleton: the skull, hands, pelvis, and feet. Only one other published caenagnathid specimen preserves all these regions, but in the present specimen, the pelvis and feet appear to be in much better condition. Together, these factors give the specimen scientific significance; and the expertly prepared mount makes for a visually striking dinosaur.
Christie’s would like to thank Professor Eberhard Frey for his assistance preparing this catalogue note.
COMPARATIVE LITERATURE
Atkins-Weltman, K. L., D. J. Simon, H. N. Woodward, G. F. Funston, and E. Snively. “A New Oviraptorosaur (Dinosauria: Theropoda) from the End-Maastrichtian Hell Creek Formation of North America.” PLOS ONE 19, no. 1 (2024): e0294901.
Balanoff, A. M., and M. A. Norell. “Osteology of Khaan mckennai (Oviraptorosauria: Theropoda).” Bulletin of the American Museum of Natural History 372 (2012): 1–77.
Brochu, C. A. “Closure of Neurocentral Sutures during Crocodilian Ontogeny: Implications for Maturity Assessment in Fossil Archosaurs.” Journal of Vertebrate Paleontology 16, no. 1 (1996): 49–62.
Clark, J. M., M. A. Norell, and T. Rowe. “Cranial Anatomy of Citipati osmolskae (Theropoda, Oviraptorosauria), and a Reinterpretation of the Holotype of Oviraptor philoceratops.” American Museum Novitates (2002): 1–24.
Coombs, W. P. “Modern Analogs for Dinosaur Nesting and Parental Behavior.” In Paleobiology of the Dinosaurs, edited by J. O. Farlow, 21–54. Geological Society of America Special Paper 238. Boulder: Geological Society of America, 1989.
Cracraft, J. “Caenagnathiformes: Cretaceous Birds Convergent in Jaw Mechanism to Dicynodont Reptiles.” Journal of Paleontology 45 (1971): 805–809.
Fawcett, K. “Scientists Discover a Large and Feathered Dinosaur That Once Roamed North America.” Smithsonian Magazine, March 20, 2014.
Funston, G. F. Anatomy, Systematics, and Evolution of Oviraptorosauria (Dinosauria, Theropoda). PhD diss., University of Alberta, 2019.
Funston, G. F. “Caenagnathids of the Dinosaur Park Formation (Campanian) of Alberta, Canada: Anatomy, Osteohistology, Taxonomy, and Evolution.” Vertebrate Anatomy Morphology Palaeontology 8 (2020): 105–153.
Funston, G. F., and P. J. Currie. “A New Caenagnathid (Dinosauria: Oviraptorosauria) from the Horseshoe Canyon Formation of Alberta, Canada, and a Reevaluation of the Relationships of Caenagnathidae.” Journal of Vertebrate Paleontology 36 (2016): e1160910.
Funston, G. F. “Osteology of the Two-Fingered Oviraptorid Oksoko avarsan (Theropoda: Oviraptorosauria).” Zoological Journal of the Linnean Society (2024): zlae011.
Funston, G. F., S. E. Mendonça, P. J. Currie, and R. Barsbold. “Oviraptorosaur Anatomy, Diversity and Ecology in the Nemegt Basin.” Palaeogeography, Palaeoclimatology, Palaeoecology 494 (2018): 101–120.
Hendrickx, C., S. A. Hartman, and O. Mateus. “An Overview of Non-Avian Theropod Discoveries and Classification.” PalArch’s Journal of Vertebrate Palaeontology 12, no. 1 (2015): 1–73.
Hone, D. W. E., A. A. Farke, and M. J. Wedel. “Ontogeny and the Fossil Record: What, If Anything, Is an Adult Dinosaur?” Biology Letters 12, no. 2 (2016): 20150947.
Ikejiri, T. “Sequence of Closure of Neurocentral Sutures in Camarasaurus (Sauropoda) and Implications for Phylogeny in Reptilia.” Journal of Vertebrate Paleontology 23, no. 3 (Suppl.) (2003): 65A.
Ji, Q., P. J. Currie, M. A. Norell, and S. Ji. “Two Feathered Dinosaurs from Northeastern China.” Nature 393, no. 6687 (1998): 753–761.
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