Yaverlandia

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Yaverlandia
Yaverlandia skull replica.png
Replica of MIWG 1530 seen from two different angles
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Maniraptoriformes
Clade: Maniraptora
Genus:† Yaverlandia
Galton, 1971
Species:
†Y. bitholus
Binomial name
†Yaverlandia bitholus
Galton, 1971

Yaverlandia (meaning "of Yaverland Point/Yaverland Battery") is a genus of theropod dinosaur known. It is from a partial fossil skull (MIWG 1530) found in Lower Cretaceous strata of the Wessex Formation (Upper Silty Bed) in the Isle of Wight, England. When MIWG 1530 was first described in a 1930 work by D. M.S. Watson, similarities were noted with the ornithopod genus Vectisaurus and the theropod genus Troodon , and in 1936 it was ultimately assigned to the former. It was recognised as a distinct genus in 1971, by Peter Galton, who re-examined the remains. Galton assigned one species, Y. bitholus, to Yaverlandia. He believed that it was the oldest member of the family Pachycephalosauridae. Subsequent research by Darren Naish suggests that Yaverlandia is instead a maniraptoran theropod.

Contents

Discovery and naming

The holotype (MIWG 1530) of Yaverlandia, consisting of two frontal bones, part of the right postorbital, and part of the left orbitosphenoid was discovered in 1930, in the Wealden Marls north of the seawall below Yaverland Battery of Sandown, on the Isle of Wight. [1] It originated from strata belonging to the Wealden Group, [1] [2] presumably the Wessex Formation, which on the Isle of Wight dates to the Hauterivian and Barremian ages. [2] [3] The specimen was first mentioned in the literature by D. M. S. Watson in an untitled article in the Proceedings of the Isle of Wight Natural History Society. [2] [4] Watson noted that it bore similarities to Vectisaurus , then very poorly understood, [1] though also noted similarities with the North American genus Troodon . [4] Six years later, W. E. Swinton assigned MIWG 1530 to Vectisaurus. [5]

In 1971, Peter Galton re-examined the specimen, creating a cast for examination. He concluded that MIWG 1530 did not belong to the same taxon as the Vectisaurus holotype, which he later assigned to the family Iguanodontidae [6] (and which is now a synonym of Mantellisaurus [2] [7] [8] ), but rather to a pachycephalosaurid. In light of its distinctiveness, Galton gave it the binomial name of Yaverlandia bitholus. [1] The genus name, Yaverlandia, refers to Yaverland, while the species name, bitholus, derives from the Latin bi ("two") and tholus ("dome"), in reference to Galton's belief that Y. bitholus bore two small domes, rather than a flat skull or a single large dome as in later pachycephalosaurids. [1] [2] In 2012, additional remains of Yaverlandia were reported, but these have not been described. [9]

Status

The status of Yaverlandia has been questioned since its naming, with Darren Naish and David Martill noting in 2002 that the holotype is fragmentary enough that it borders on being a nomen dubium . [2] Naish later suggested that Yaverlandia was not a pachycephalosaurid, as initially suggested, but rather may have been a theropod, [10] and more specifically a maniraptoran. [11] Traits indicating a position within Theropoda include a cerebral concavity with two distinct lobes, a narrow olfactory tract with small olfactory bulbs, and concave ventral (bottom) margins to the orbits (eye sockets). [12] Furthermore, a computerised tomography (CT) scan of the specimen found cavities within the bones similar to those found in maniraptorans. [13] In 2011, Naish suggested that it was a troodontid, and prepared a redescription of the genus, but this has yet to be published. [12] [13]

Description

Comparisons with the skulls of Hypsilophodon and Stegoceras led Peter Galton to note that, despite being fused into a single element, [1] [2] both frontal bones were preserved in the holotype of Yaverlandia. Galton diagnosed Yaverlandia based on the presence of two small domes (one per frontal), a dorsal (upper) surface covered in small pits, a frontal which contributed to the edge of the orbit (eye socket) and was not excluded from it by the prefrontal bone, and a supratemporal fenestra which was not constricted by the postorbital bone, [1] nor reduced as in late pachycephalosaurid genera. [2] The kind of pitting observed on the dorsal surfaces of each frontal is not found in any known pachycephalosaurid taxon, [12] although something loosely similar is known in Homalocephale. [12] [14] The depressions formed by each cerebral hemisphere were concave, differing from those of Pachycephalosaurus and Stegoceras in that they were not enclosed in bone ventrally (on their bottom side); [1] the presence of two distinct lobes is part of the reason Yaverlandia has been tentatively assigned to Maniraptora. [12] [13]

Palaeoecology

A selection of Wessex Formation dinosaurs. On the left is Iguanodon. In the foreground is a group of Hypsilophodon being pursued by an Eotyrannus. In the right background is a Neovenator. In the midground is a pair of basal ornithomimosaurs. Wessex Formation dinosaurs.jpg
A selection of Wessex Formation dinosaurs. On the left is Iguanodon. In the foreground is a group of Hypsilophodon being pursued by an Eotyrannus. In the right background is a Neovenator. In the midground is a pair of basal ornithomimosaurs.

The holotype of Yaverlandia presumably heralds from the Wessex Formation. [2] [15] Sedimentological data suggests that the depositional environment of the Wessex Formation was a floodplain intersected by fluvial (river) and lacustrine (lake) deposits. Water levels likely varied throughout the year, [16] due to there being more evaporation than precipitation, though precipitation was regardless quite high. The Wessex seems to have regularly experienced extreme storms [17] and periodic flood events, resulting in debris flows which would have deposited dead organisms in ponds. [18] Burned plant and insect material and fusain suggests that the environment experienced frequent wildfires, stifling for the most part the dense growth of gymnosperms. [16] [18] Much of the flora of the formed of low ground cover, consisting primarily of pteridophytes, with occasional stands of conifers, cycads and the tree fern Tempskya . [16] Most vertebrate material from the Wessex Formation originates from plant debris beds, resulting from the aforementioned flooding events. [18]

Aside from Yaverlandia, the dinosaur fauna of the Isle of Wight includes the theropods Aristosuchus , Calamospondylus , Ceratosuchops , Eotyrannus , Neovenator , Ornithodesmus , Riparovenator and Thecocoelurus , the sauropods Chondrosteosaurus , Eucamerotus and Ornithopsis , [19] [20] the thyreophorans Polacanthus [20] and Vectipelta , [21] and the ornithopods Brighstoneus , [22] Comptonatus , [23] Hypsilophodon , Iguanodon , [20] Mantellisaurus , [24] Valdosaurus [19] [20] and Vectidromeus. [25] The pterosaur fauna of the Wessex Formation consists of Coloborhynchus , Caulkicephalus , Istiodactylus , [26] Vectidraco , [27] and Wightia ; [28] multiple unnamed pterosaur taxa, including a ctenochasmatid, are also known. [26] Neosuchian crocodyliforms include Bernissartia , Koumpiodontosuchus [29] and Vectisuchus . [30] Limited evidence exists of elasmosaurids and leptocleidid plesiosaurs. [31] The mammal fauna of the Wessex Formation includes the multituberculate Eobataar [32] and the spalacotheriid Yaverlestes . [33] Albanerpetontid amphibians are represented by Wesserpeton . [34] The fish fauna of the Wessex Formation, both bony and cartilaginous, is extensive, including hybodontiform and modern sharks (Selachii), pycnodontiforms, Lepidotes and Scheenstia . [35] Invertebrates are represented by an assortment of non-biting midges, [36] hymenopterans (wasps) including multiple parasitoid taxa, [37] coleopterans (beetles), the avicularoid spider Cretamygale , [38] and the ostracod Cypridea. [39]

References

  1. 1 2 3 4 5 6 7 8 Galton, P.M. (1971) "A primitive dome-headed dinosaur (Ornithischia: Pachycephalosauridae) from the Lower Cretaceous of England and the function of the dome of pachycephalosaurids". Journal of Paleontology, Vol. 45, No. 1, Pages 40–47.
  2. 1 2 3 4 5 6 7 8 9 Naish, D., and Martill, D., 2001, "Boneheaded and Horned Dinosaurs". In: Martill, D. and Naish, D. (eds.), Dinosaurs of the Isle of Wight The Palaeontological Association, pp. 140–146
  3. ↑ Marsden, Marie K.; Gunn, Joshua; Maidment, Susannah C. R.; Nichols, Gary; Wheeley, James R.; Russell, Catherine E.; Boomer, Ian; Stukins, Stephen; Butler, Richard J. (6 January 2025). "Palaeoenvironment and taphonomy of the Hypsilophodon Bed, Lower Cretaceous Wessex Formation, Isle of Wight". Journal of the Geological Society. 182 (1). doi:10.1144/jgs2024-046.
  4. 1 2 Watson, D.M.S (1930) Proceedings of the Isle of Wight Natural History Society. 2, 60.
  5. ↑ Swinton, W.E. (1936). The dinosaurs of the Isle of Wight. Proceedings of the Geologists' Association, 47, 204–220.
  6. ↑ Galton, Peter M. (1976). "The Dinosaur Vectisaurus valdensis (Ornithischia: Iguanodontidae) from the Lower Cretaceous of England". Journal of Paleontology. 50 (5): 976–984. ISSN   0022-3360.
  7. ↑ Norman, David B. (1990), Carpenter, Kenneth; Currie, Philip J. (eds.), "A review of Vectisaurus valdensis, with comments on the family Iguanodontidae", Dinosaur Systematics: Approaches and Perspectives, Cambridge: Cambridge University Press, pp. 147–162, ISBN   978-0-521-43810-0 , retrieved 2025-11-04
  8. ↑ Paul, Gregory S. (2008). "A revised taxonomy of the iguanodont dinosaur genera and species". Cretaceous Research. 29 (2): 192–216. doi:10.1016/j.cretres.2007.04.009.
  9. ↑ Austen, Peter A.; Batten, David J. (2018-04-01). "English Wealden fossils: an update" . Proceedings of the Geologists' Association. 129 (2): 171–201. Bibcode:2018PrGA..129..171A. doi:10.1016/j.pgeola.2018.02.007. ISSN   0016-7878.
  10. ↑ Naish, Darren; Sweetman, Steven C. (2011-08-01). "A tiny maniraptoran dinosaur in the Lower Cretaceous Hastings Group: Evidence from a new vertebrate-bearing locality in south-east England". Cretaceous Research. 32 (4): 464–471. doi:10.1016/j.cretres.2011.03.001. ISSN   0195-6671.
  11. ↑ Naish, Darren; Martill, David M. (2008). "Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: Ornithischia" (PDF). Journal of the Geological Society, London. 165 (3): 613–623. Bibcode:2008JGSoc.165..613N. doi:10.1144/0016-76492007-154. S2CID   129624992.
  12. 1 2 3 4 5 Sullivan, R. M., 2006: A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia). New Mexico Museum of Natural History Bulletin 35: 347-365
  13. 1 2 3 Naish, Darren (2011). "Theropod dinosaurs". In Batten, David J. (ed.). English wealden fossils. Field guides to fossils. London: Palaeontological Association. pp. 529, 557–559. ISBN   978-1-4443-6711-9.
  14. ↑ Maryańska, T.; Osmólska, H. (1974). "Pachycephalosauria, a new suborder of ornithischian dinosaurs" (PDF). Palaeontologica Polonica (30): 45−102.
  15. ↑ Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, Europe)". In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 556-563. ISBN   0-520-24209-2.
  16. 1 2 3 Insole, Allan N.; Hutt, Stephen (1994). "The palaeoecology of the dinosaurs of the Wessex Formation (Wealden Group, Early Cretaceous), Isle of Wight, Southern England" . Zoological Journal of the Linnean Society. 112 (1–2): 197–215. doi:10.1111/j.1096-3642.1994.tb00318.x.
  17. ↑ Marsden, Marie K.; Gunn, Joshua; Maidment, Susannah C. R.; Nichols, Gary; Wheeley, James R.; Russell, Catherine E.; Boomer, Ian; Stukins, Stephen; Butler, Richard J. (2025-01-06). "Palaeoenvironment and taphonomy of the Hypsilophodon Bed, Lower Cretaceous Wessex Formation, Isle of Wight". Journal of the Geological Society. 182 (1): jgs2024–046. Bibcode:2025JGSoc.182...46M. doi: 10.1144/jgs2024-046 .
  18. 1 2 3 Pond, Stuart; Strachan, Sarah-Jane; Raven, Thomas J.; Simpson, Martin I.; Morgan, Kirsty; Maidment, Susannah C. R. (2023). "Vectipelta barretti , a new ankylosaurian dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, UK" . Journal of Systematic Palaeontology. 21 (1). Bibcode:2023JSPal..2110577P. doi:10.1080/14772019.2023.2210577. ISSN   1477-2019.
  19. 1 2 Barker, C.T.; Hone, D.; Naish, D.; Cau, A.; Lockwood, J.; Foster, B.; Clarkin, C.; Schneider, P.; Gostling, N. (2021). "New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae". Scientific Reports. 11 (1): 19340. Bibcode:2021NatSR..1119340B. doi:10.1038/s41598-021-97870-8. PMC   8481559 . PMID   34588472.
  20. 1 2 3 4 Martill, D. M.; Hutt, S. (1996). "Possible baryonychid dinosaur teeth from the Wessex Formation (Lower Cretaceous, Barremian) of the Isle of Wight, England". Proceedings of the Geologists' Association. 107 (2): 81–84. Bibcode:1996PrGA..107...81M. doi:10.1016/S0016-7878(96)80001-0.
  21. ↑ Pond, Stuart; Strachan, Sarah-Jane; Raven, Thomas J.; Simpson, Martin I.; Morgan, Kirsty; Maidment, Susannah C. R. (2023-01-01). "Vectipelta barretti, a new ankylosaurian dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, UK" . Journal of Systematic Palaeontology. 21 (1). Bibcode:2023JSPal..2110577P. doi:10.1080/14772019.2023.2210577. ISSN   1477-2019. S2CID   259393929.
  22. ↑ Lockwood, Jeremy A. F.; Martill, David M.; Maidment, Susannah C. R. (2021-11-10). "A new hadrosauriform dinosaur from the Wessex Formation, Wealden Group (Early Cretaceous), of the Isle of Wight, southern England". Journal of Systematic Palaeontology. 19 (12): 847–888. Bibcode:2021JSPal..19..847L. doi: 10.1080/14772019.2021.1978005 . ISSN   1477-2019. S2CID   244067410.
  23. ↑ Lockwood, Jeremy A. F.; Martill, David M.; Maidment, Susannah C. R. (2024-12-31). "Comptonatus chasei, a new iguanodontian dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, southern England". Journal of Systematic Palaeontology . 22 (1). Bibcode:2024JSPal..2246573L. doi: 10.1080/14772019.2024.2346573 . ISSN   1477-2019.
  24. ↑ Carpenter, K. & Ishida, Y. (2010). "Early and "Middle" Cretaceous Iguanodonts in Time and Space". Journal of Iberian Geology . 36 (2): 145–164. doi: 10.5209/rev_JIGE.2010.v36.n2.3 .
  25. ↑ Longrich, Nicholas R.; Martill, David M.; Munt, Martin; Green, Mick; Penn, Mark; Smith, Shaun (2024-02-01). "Vectidromeus insularis, a new hypsilophodontid dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, England" . Cretaceous Research. 154 105707. Bibcode:2024CrRes.15405707L. doi:10.1016/j.cretres.2023.105707. ISSN   0195-6671.
  26. 1 2 Martill, David M.; Coram, Robert A. (2020-08-01). "Additional evidence for very large wing-span pterosaurs in the Wessex Formation (Early Cretaceous, Barremian) of southern England" . Proceedings of the Geologists' Association. 131 (3): 293–300. Bibcode:2020PrGA..131..293M. doi:10.1016/j.pgeola.2019.05.002. ISSN   0016-7878.
  27. ↑ Naish, D.; Simpson, M.; Dyke, G. (2013). Farke, Andrew A (ed.). "A New Small-Bodied Azhdarchoid Pterosaur from the Lower Cretaceous of England and Its Implications for Pterosaur Anatomy, Diversity and Phylogeny". PLOS ONE. 8 (3) e58451. Bibcode:2013PLoSO...858451N. doi: 10.1371/journal.pone.0058451 . PMC   3601094 . PMID   23526986.
  28. ↑ Martill, David M.; Green, Mick; Smith, Roy E.; Jacobs, Megan L.; Winch, John (2020-09-01). "First tapejarid pterosaur from the Wessex Formation (Wealden Group: Lower Cretaceous, Barremian) of the United Kingdom" . Cretaceous Research. 113 104487. Bibcode:2020CrRes.11304487M. doi:10.1016/j.cretres.2020.104487. ISSN   0195-6671.
  29. ↑ Sweetman, Steven; Pedreira-Segade, Ulysse; Vidovic, Steven (2014). "A new bernissartiid crocodyliform from the Lower Cretaceous Wessex Formation (Wealden Group, Barremian) of the Isle of Wight, southern England". Acta Palaeontologica Polonica. doi:10.4202/app.00038.2013. ISSN   0567-7920.
  30. ↑ Buffetaut, Eric; Hutt, Stephen (1980-07-31). "Vectisuchus leptognathus, n. g. n. sp., a slender-snouted goniopholid crocodilian from the Wealden of the Isle of Wight" . Neues Jahrbuch für Geologie und Paläontologie - Monatshefte (7): 385–390. doi:10.1127/njgpm/1980/1980/385.
  31. ↑ Kear, Benjamin P.; Barrett, Paul M. (2011-03-01). "Reassessment of the Lower Cretaceous (Barremian) pliosauroid Leptocleidus superstes Andrews, 1922 and other plesiosaur remains from the nonmarine Wealden succession of southern England" . Zoological Journal of the Linnean Society. 161 (3): 663–691. doi:10.1111/j.1096-3642.2010.00648.x. ISSN   0024-4082.
  32. ↑ Sweetman, Steven C. (2009). "A New Species of the Plagiaulacoid Multituberculate Mammal Eobaatar from the Early Cretaceous of Southern Britain". Acta Palaeontologica Polonica. 54 (3): 373–384. doi: 10.4202/app.2008.0003 . ISSN   0567-7920.
  33. ↑ Sweetman, Steven C. (2008). "A Spalacolestine Spalacotheriid (mammalia, Trechnotheria) from the Early Cretaceous (barremian) of Southern England and Its Bearing on Spalacotheriid Evolution" . Palaeontology. 51 (6): 1367–1385. Bibcode:2008Palgy..51.1367S. doi:10.1111/j.1475-4983.2008.00816.x. ISSN   1475-4983.
  34. ↑ Sweetman, Steven; Gardner, James (2013-06-01). "A new albanerpetontid amphibian from the Early Cretaceous (Barremian) Wessex Formation of the Isle of Wight, southern England". Acta Palaeontologica Polonica. 58 (2): 295–324. doi: 10.4202/app.2011.0109 . ISSN   0567-7920.
  35. ↑ Sweetman, Steven C.; Goedert, Jean; Martill, David M. (2014-11-01). "A preliminary account of the fishes of the Lower Cretaceous Wessex Formation (Wealden Group, Barremian) of the Isle of Wight, southern England". Biological Journal of the Linnean Society. 113 (3): 872–896. doi:10.1111/bij.12369. ISSN   0024-4066.
  36. ↑ Baranov, Viktor; Giłka, Wojciech; Zakrzewska, Marta; Jarzembowski, Edmund (2019-03-01). "New non-biting midges (Diptera: Chironomidae) from Lower Cretaceous Wealden amber of the Isle of Wight (UK)" . Cretaceous Research. 95: 138–145. Bibcode:2019CrRes..95..138B. doi:10.1016/j.cretres.2018.11.012. ISSN   0195-6671.
  37. ↑ Perkovsky, Evgeny E.; Olmi, Massimo; Müller, Patrick; Guglielmino, Adalgisa; Jarzembowski, Edmund A.; Capradossi, Leonardo; Rasnitsyn, Alexandr P. (2021-05-01). "A review of the fossil Embolemidae (Hymenoptera: Chrysidoidea), with description of seven new species and history of the family" . Cretaceous Research. 121 104708. Bibcode:2021CrRes.12104708P. doi:10.1016/j.cretres.2020.104708. ISSN   0195-6671.
  38. ↑ Selden, Paul A. (2002). "First British Mesozoic Spider, From Cretaceous Amber Of The Isle Of Wight, Southern England". Palaeontology. 45 (5): 973–983. Bibcode:2002Palgy..45..973S. doi:10.1111/1475-4983.00271. hdl: 1808/8357 . ISSN   1475-4983.
  39. ↑ Penn, Simon J.; Sweetman, Steven C. (2023-03-01). "Microvertebrate-rich gutter casts from the basal Wessex Formation (Wealden Group, Lower Cretaceous) of Dungy Head, Dorset: Insights into the palaeoecology and palaeoenvironment of a non-marine wetland" . Cretaceous Research. 143 105397. Bibcode:2023CrRes.14305397P. doi:10.1016/j.cretres.2022.105397. ISSN   0195-6671.
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