Kilmaluag Formation

Kilmaluag Formation
Stratigraphic range: Bathonian 167.4–166.5 Ma
↓
Sediments of the Kilmaluag Formation overlain by Paleogene lava
Type Formation
Unit of Great Estuarine Group
Underlies Skudiburgh Formation
Overlies Duntulm Formation
Thickness Up to 25 m
Lithology
Primary Calcareous Mudstone, Limestone
Location
Country Scotland
Extent Throughout Inner Hebrides, including Isle of Skye, Isle of Muck, and Isle of Eigg
Type section
Named for Kilmaluag Bay in the North of Skye

The Kilmaluag Formation is a Middle Jurassic geologic formation in Scotland. It was formerly known as the Ostracod Limestone for the abundance of fossil freshwater ostracods within it. The Kilmaluag Formation is very fossiliferous, with ostracods, gastropods, bivalves and vertebrate fossil remains. Vertebrate fossils include fish, crocodiles, mammals, lizards and some large reptile remains including dinosaurs.

The Kilmaluag Formation is Bathonian,and dates to around 167 million years old. It is part of the Great Estuarine Group of the Hebrides Basin, a series of sediments laid down when the Scottish Hebrides was part of a warm shallow sea running between what is now mainland Scotland the Outer Hebrides.[1]

The Kilmaluag Formation is composed of dolomitised limestones, fine grain sandstones, and mudstones, indicating that it alternated between a shallow environment, and lagoonal mudflats as the basin subsided and rose, causing sea levels to fluctuate.[2] These mudflats sometimes dried out to form desiccation cracks. The Kilmaluag is unusual among the Estuarine Group for the freshwater environment it preserves - whereas many other Formations in this group are predominantly brackish to marine in nature.[1] In many beds you can find freshwater gastropods and bivalves including Viviparus and Unio, and freshwater ostracods such as Darwinula.[2][1]

Many vertebrate fossils are found in the Kilmaluag, and it has been explored by palaeontologists since the 1970s, when the first mammal fossil was found there by Michael Waldman. He returned with fellow palaeontologist Robert Savage and they collected more fossils and named two new species from the area: the Docodont Borealestes serendipitus, and the tritylodontid, Stereognathus hebridicus[3] (although S. hebridicus is now thought to be a junior synonym to S. ooliticus)[4]. Many other fossils are found in the Kilmaluag, including members of other Mesozoic mammal groups, turtles, reptiles, and amphibians[5]. The most recent discoveries in the Kilmaluag Formation include Palaeoxonodon ooliticus[6] and Wareolestes rex.[7] and the tooth of a sauropod dinosaur.[8]

Vertebrate Paleobiota

Amphibians

Amphibians reported from the Kilmaluag Formation
Genus Species Location Stratigraphic position Material Notes Images
Marmorerpeton[5] M. kermacki Cladach a'Ghlinne Salamander
Caudata[5] Indeterminate Cladach a'Ghlinne Referred to as "Kirtlington 'Salamander A'"

Turtles

Turtles reported from the Kilmaluag Formation
Genus Species Location Stratigraphic position Material Notes Images
Eileanchelys[9] E. waldmani Cladach a'Ghlinne Partial skull and association of 5-6 individuals with skull and shell material.
Testudines[5] Indeterminate Cladach a'Ghlinne

Lepidosauromorphs

Lepidosauromorphs reported from the Kilmaluag Formation
Genus Species Location Stratigraphic position Material Notes Images
Marmoretta[10] M. oxoniensis Cladach a'Ghlinne Partial associated skeleton Stem-lepidosauromorph
cf. Paramacellodus[5] Indeterminate Cladach a'Ghlinne
Parviraptor [5] Indeterminate Cladach a'Ghlinne Stem-snake (disputed)
Squamata[5] Indeterminate Cladach a'Ghlinne Distinct from other taxa known from the British Bathonian, new gen et sp indet.

Choristoderes

Choristoderes reported from the Kilmaluag Formation
Genus Species Location Stratigraphic position Material Notes Images
Cteniogenys[5] Indeterminate Cladach a'Ghlinne Partial skull

Dinosaurs

Dinosaurs reported from the Kilmaluag Formation
Genus Species Location Stratigraphic position Material Notes Images
Eusauropoda[8] Indeterminate Cladach a'Ghlinne Tooth

Mammaliamorphs

Mammaliamorphs reported from the Kilmaluag Formation
Genus Species Location Stratigraphic position Material Notes Images
Borealestes[11] B. serendipitus Cladach a'Ghlinne Toothed jaw fragments, referred partial skeleton[12]
Krusatodon[5] Indeterminate Cladach a'Ghlinne Molar
Palaeoxonodon[6] P. ooliticus Cladach a'Ghlinne Three partial left dentaries[13]
Stereognathus S. ooliticus[4] Cladach a'Ghlinne Partial toothed jaw, isolated teeth
Wareolestes[7] W. rex Partial left dentary

See also

References

  1. 1 2 3 Andrews, J. E. 1985 The sedimentary facies of a late Bathonian regressive episode: the Kilmaluag and Skudiburgh Formations of the Great Estuarine Group, Inner Hebrides, Scotland. Journal of the Geological Society of London, 142, 1119-37.
  2. 1 2 Barron, A. J. M., Lott, G. K. and Riding, J. B. 2012 Stratigraphical framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf. British Geological Survey Research Report, RR/11/06. British Geological Survey, Keyworth
  3. ↑ Waldman, M and Savage, R.J.G 1972 The first Jurassic mammal from Scotland. Journal of the Geological Society of London 128:119-125
  4. 1 2 Panciroli, Elsa; Walsh, Stig; Fraser, Nicholas C.; Brusatte, Stephen L.; Corfe, Ian (2017-09-03). "A reassessment of the postcanine dentition and systematics of the tritylodontid Stereognathus (Cynodontia, Tritylodontidae, Mammaliamorpha), from the Middle Jurassic of the United Kingdom". Journal of Vertebrate Paleontology. 37 (5): e1351448. doi:10.1080/02724634.2017.1351448. hdl:10138/230155. ISSN 0272-4634.
  5. 1 2 3 4 5 6 7 8 9 Evans, S., Barrett, P., Hilton, J., Butler R.J., Jones, M.E.H., Liang, M-.M., Parrish, J.C., Rayfield, E.J., Sigogneau-Russell, D., and Underwood, C.J. 2005. The Middle Jurassic vertebrate assemblage of Skye, Scotland. 36-39. In P. Barrett and S. Evans (eds). Proceedings of the Ninth Symposium on Mesozoic Terrestrial Ecosystems and Biota. Natural History Museum, London.
  6. 1 2 Close, Roger A.; Davis, Brian M.; Walsh, Stig; Wolniewicz, Andrzej S.; Friedman, Matt; Benson, Roger B. J. (2015-11-13). "A lower jaw of Palaeoxonodon from the Middle Jurassic of the Isle of Skye, Scotland, sheds new light on the diversity of British stem therians". Palaeontology. 59 (1): 155–169. doi:10.1111/pala.12218. ISSN 0031-0239.
  7. 1 2 Panciroli, Elsa; Benson, Roger B. J.; Walsh, Stig (2017-05-04). "The dentary of Wareolestes rex (Megazostrodontidae): a new specimen from Scotland and implications for morganucodontan tooth replacement". Papers in Palaeontology. 3 (3): 373–386. doi:10.1002/spp2.1079. ISSN 2056-2802. line feed character in |title= at position 31 (help)
  8. 1 2 Barrett, Paul M. (2006/03). "A sauropod dinosaur tooth from the Middle Jurassic of Skye, Scotland". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 97 (1): 25–29. doi:10.1017/S0263593300001383. ISSN 1473-7116. Check date values in: |date= (help)
  9. ↑ Anquetin, J.; Barrett, P.M.; Jones, M.E.H.; Moore-Fay, S.; Evans, S.E. (2009). "A new stem turtle from the Middle Jurassic of Scotland: new insights into the evolution and palaeoecology of basal turtles". Proceedings of the Royal Society B: Biological Sciences. 276 (1658): 879–886. doi:10.1098/rspb.2008.1429. ISSN 0962-8452. PMC 2664364. PMID 19019789.
  10. ↑ Waldman, M.; Evans, S. E. (1994). "Lepidosauromorph reptiles from the Middle Jurassic of Skye". Zoological Journal of the Linnean Society. 112: 135–150. doi:10.1111/j.1096-3642.1994.tb00315.x.
  11. ↑ WALDMAN, MICHAEL; SAVAGE, ROBERT JOSEPH GAY (1972-03). "The first Jurassic mammal from Scotland". Journal of the Geological Society. 128 (2): 119–125. doi:10.1144/gsjgs.128.2.0119. ISSN 0016-7649. Check date values in: |date= (help)
  12. ↑ Panciroli, Elsa; Schultz, Julia A.; Luo, Zhe-Xi (2018-08-31). "Morphology of the petrosal and stapes of Borealestes (Mammaliaformes, Docodonta) from the Middle Jurassic of Skye, Scotland". Papers in Palaeontology. doi:10.1002/spp2.1233. ISSN 2056-2802. line feed character in |title= at position 53 (help)
  13. ↑ Panciroli, Elsa; Benson, Roger; Butler, Richard (2018). "New partial dentaries of amphitheriid mammalian Palaeoxonodon ooliticus from Scotland, and posterior dentary morphology in early cladotherians". Acta Palaeontologica Polonica. 63. doi:10.4202/app.00434.2017. ISSN 0567-7920.
  • Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 31 July 2014. Retrieved 8 July 2014.
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