Groenlandaspis

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Groenlandaspis
Temporal range: Late Devonian
Groenlandaspis.png
Artist's reconstruction of G. riniensis
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class:† Placodermi
Order:† Arthrodira
Family:† Groenlandaspididae
Genus:† Groenlandaspis
Heintz, 1932 [1]
Type species
Groenlandaspis mirabilis
Heintz, 1932 [2]
Other species
  • G. pennsylvanicaDaeschler et al., 2003 [3]
  • G. antarcticaRitchie, 1975 [4]
  • G. riniensis(Gess and Hiller, 1995) [5]
  • G. disjectus(Woodward, 1891) (originally Coccosteus disjectus) [4]
  • G. potyiOlive et al., 2015 [6]
  • G. theroni(Chaloner et al., 1980) [3]
  • G. seniJanvier, P. and A. Ritchie. 1977 [7]
  • G. thoreziHeintz, 1932 [2]

Groenlandaspis is an extinct genus of arthrodire from the Late Devonian. Fossils of the different species are found in late Devonian strata in all continents except eastern Asia. The generic name commemorates the fact that the first specimens of the type species were found in Greenland.

Contents

Description

As with all other arthrodires, Groenlandaspis had a joint in the back of its head with its thoracic armor, allowing for its head to be thrown back, increasing its gape. However, as its head is somewhat compressed in comparison with many other arthrodires, and as the dorsal side came to a low, pyramid-like peak, it is believed that Groenlandaspis could not crane its head back very far. It was a relatively small fish, only 7.5 centimetres (3.0 in) in length on average, [8] though one unusually large species, G. riniensis, reached almost a metre in length [9] It lived in coastal and fluvial waters, where it is thought to have fed on either very small prey, or detritus; the small dental plates in its mouth strongly suggest that it was incapable of tackling large prey. [8] The possibility that the plates may have been used to, at times, feed on bivalves has also been muted. [9]

The body shape of the largest species G. riniensis’ suggests that it was most likely a benthic fish. The presence of crushing tooth plates in the form of flat, noded infragnathals and superagnathals suggest that the species' diet may have included prey with hard external shells such as molluscs, crustaceans or arthropods. [10] The armor length of G. riniensis, according to the original description, was approximately 40 cm (15.7 in), with the head shield having a very broad marginal plate and narrow pineal plate, with the nuchal relatively narrow, being approximately half as broad as it is long. The trunk shield of this species was characterized as having an anterior lateral plate which is almost as broad as long with a relatively straight anterior margin; the median dorsal plate is low with an apex that is posteriorly directed; its posterior dorsolateral plate is very narrow with inflexion of the main lateral line canal situated very close to posterior margin. This species has ornamentation of widely spaced, coarse tubercles. [11]

Groenlandaspis is unusual among placoderms in that it is known what color it was; preserved pigment cells in its fossils indicate that its posterior was red and its anterior was silvery-white in a countershaded pattern, camouflaging it in the murky, silty waters of the rivers in which it dwelled. [12]

Species

Groenlandaspis riniensis is one of two arthrodire placoderms described in 1999 from the Waterloo Farm lagerstätte in South Africa, [13] [14] with a third species having been subsequently described. [15] The species name ‘riniensis’ derived from Rini or Rhini, the traditional isiXhosa name for Makhanda/Grahamstown, [11] making it the first ever vertebrate fossil to have an isiXhosa derived scientific name. G. riniensis appears to have spent its entire life cycle within the Waterloo Farm estuary as it is represented by a full ontogenetic series. [10] Evidence from other Late Devonian localities with similar placoderm taxa which suggest that while many larvae or small juveniles stayed in the littoral zone close to adult habitats, others may have moved upriver to avoid predation. [10] G. riniensis represents the most frequently preserved fish taxon from the Waterloo Farm site, and may have been the most common vertebrate within the palaeoenvironment, though its frequent preservation may be influenced by preservational bias. [10]

A scatter of dissassociated adult Groenlandaspis riniensis trunk armour plates at the Waterloo Farm lagerstatte (anteriolateral at left, posterior dorsolateral at right (both upside down) and large elongate spinal towards the bottom). ASCATT~1.jpg
A scatter of dissassociated adult Groenlandaspis riniensis trunk armour plates at the Waterloo Farm lagerstätte (anteriolateral at left, posterior dorsolateral at right (both upside down) and large elongate spinal towards the bottom).
Groenlandaspis riniensis hatchling from the Waterloo Farm lagerstatte. Groenlandaspis riniensis hatchling from the Waterloo Farm lagerstatte.jpg
Groenlandaspis riniensis hatchling from the Waterloo Farm lagerstätte.

Related Research Articles

<span class="mw-page-title-main">Placodermi</span> Class of fishes (fossil)

Placodermi is a class of armoured prehistoric fish, known from fossils, which lived from the Silurian to the end of the Devonian period. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked, depending on the species. Placoderms were among the first jawed fish; their jaws likely evolved from the first of their gill arches.

<i>Dunkleosteus</i> Extinct genus of placoderm fish

Dunkleosteus is an extinct genus of large armored, jawed fishes that existed during the Late Devonian period, about 382–358 million years ago. It consists of ten species, some of which are among the largest placoderms to have ever lived: D. terrelli, D. belgicus, D. denisoni, D. marsaisi, D. magnificus, D. missouriensis, D. newberryi, D. amblyodoratus, and D. raveri. The largest and most well known species is D. terrelli, which grew up to 8.79 m (28.8 ft) long and 4 t in weight. Dunkleosteus could quickly open and close its jaw, like modern-day suction feeders, and had a bite force of 4,414 N at the tip and 5,363 N at the blade edge. Numerous fossils of the various species have been found in North America, Poland, Belgium, and Morocco.

<span class="mw-page-title-main">Arthrodira</span> Extinct order of fishes

Arthrodira is an order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches. Arthrodires were the largest and most diverse of all groups of Placoderms.

<i>Bothriolepis</i> Diverse genus of placoderm fishes of the Devonian

Bothriolepis was a widespread, abundant and diverse genus of antiarch placoderms that lived during the Middle to Late Devonian period of the Paleozoic Era. Historically, Bothriolepis resided in an array of paleo-environments spread across every paleocontinent, including near shore marine and freshwater settings. Most species of Bothriolepis were characterized as relatively small, benthic, freshwater detritivores, averaging around 30 centimetres (12 in) in length. However, the largest species, B. rex, had an estimated bodylength of 170 centimetres (67 in). Although expansive with over 60 species found worldwide, comparatively Bothriolepis is not unusually more diverse than most modern bottom dwelling species around today.

<i>Titanichthys</i>

Titanichthys is an extinct genus of giant, aberrant marine placoderm from shallow seas of the Late Devonian of Morocco, Eastern North America, and possibly Europe. Many of the species approached Dunkleosteus in size and build. Unlike its relative, however, the various species of Titanichys had small, ineffective-looking mouth-plates that lacked a sharp cutting edge. It is assumed that Titanichthys was a filter feeder that used its capacious mouth to swallow or inhale schools of small, anchovy-like fish, or possibly krill-like zooplankton, and that the mouth-plates retained the prey while allowing the water to escape as it closed its mouth. A study has since confirmed this assumption as its jaws are functionally closer to that of filter feeders like baleen whales and basking sharks, and it appears to have developed from benthic durophagists that became pelagic suspension feeders. This would make it the first (known) large-sized vertebrate filter feeder. Titanichthys reached a length of 7 m (23 ft) though in older paper it was estimated at 7.5 m (25 ft).

<i>Dinichthys</i> Extinct genus of placoderm fish

Dinichthys is an extinct monospecific genus of giant, marine arthrodire placoderm from the Late Devonian, comparable in size, shape, and ecological role to the better-known Dunkleosteus. Fossils were recovered from the Ohio Shale Formation along the Olentangy River in Delaware County, Ohio.

<span class="mw-page-title-main">Dunkleosteidae</span> Extinct family of fishes

Dunkleosteidae is an extinct family of arthrodire placoderms that lived during the Devonian period. The gigantic apex predator Dunkleosteus terrelli is the best known member of this group.

<i>Phyllolepis</i>

Phyllolepis is the type genus of Phyllolepida, an extinct taxon of arthrodire placoderm fish from the middle to late Devonian. The species of Phyllolepis, themselves, are restricted to the Famennian-aged freshwater strata of the Late Devonian, around 360 million years ago. Fossils of this genus have been found primarily in Europe and North America. The end of the Devonian saw them disappear in a mass extinction.

<i>Eastmanosteus</i>

Eastmanosteus is a fossil genus of dunkleosteid placoderms. It was closely related to the giant Dunkleosteus, but differed from that genus in size, in possessing a distinctive tuberculated bone ornament, a differently shaped nuchal plate and a more zig-zagging course of the sutures of the skull roof.

<i>Gorgonichthys</i> Genus of fishes (fossil)

Gorgonichthys is extinct monospecific genus of large arthrodire placoderm. Fossils are found in the Upper Famennian Cleveland Shales of Late Devonian in Ohio. The type species is Gorgonichthys clarki.

<i>Incisoscutum</i> Genus of extinct placoderms

Incisoscutum is an extinct genus of arthrodire placoderm from the Early Frasnian Gogo Reef, from Late Devonian Australia. The genus contains two species I. ritchiei, named after Alex Ritchie, a palaeoichthyologist and senior fellow of the Australian Museum, and I. sarahae, named after Sarah Long, daughter of its discoverer and describer, John A. Long.

<i>Holdenius</i> Extinct genus of fishes

Holdenius is an extinct genus of arthrodire placoderm fish which lived during the Late Devonian period.

<i>Mcnamaraspis</i>

Mcnamaraspis is an extinct monospecific genus of arthrodire placoderm that inhabited the ancient reef system of north Western Australia during the Frasnian epoch of the Late Devonian period. The type specimen was found and described by John A. Long from the Gogo Formation near Fitzroy Crossing. This fossil fish showed new anatomical features in arthrodires, like the well-preserved annular (ring-shaped) cartilages of the snout, previously inferred to be present by Erik Stensiö of Sweden. It is occasionally referred to as "The Gogo Fish" after the locale the holotype was excavated from.

<i>Priscomyzon</i> Extinct lamprey from late Devonian South Africa

Priscomyzon riniensis is an extinct lamprey that lived some 360 million years ago during the Famennian in a marine or estuarine environment in South Africa. This small agnathan is anatomically similar to the Mazon Creek lampreys, but is some 35 million years older. Its key developments included the first known large oral disc, circumoral teeth and a branchial basket.

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<span class="mw-page-title-main">Waterloo Farm lagerstätte</span> Site in South Africa with a wide range of fossils from high-latitudinal Gondwana

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<i>Diplacanthus</i> Extinct genus of Devonian spiny sharks.

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Isityumzi mlomomde is a weakly described fossil lungfish based on one complete parasphenoid, tooth plates fragments and scales from the Late Devonian Sarcopterygians. It represents the only record of Late Devonian lungfish remains from western Gondwana.

The Mandagery Sandstone is a Late Devonian geological formation in New South Wales, Australia. It is one of several famed Australian lagerstätten, with thousands of exceptional fish fossils found at a site near the town of Canowindra.

References

  1. ↑ "Fossilworks: Groenlandaspis". fossilworks.org.
  2. 1 2 Heintz, A., 1932: Beitrag zur Kenntniss der Devonischen Fischfaunen Ost-Grönlands. Skrifter om Svalbard og Ishavet, 42: 1–27.
  3. 1 2 Daeschler, E. B., Frumes, A. C. & Mullison, C. F., 2003: Groenlandaspidid Placoderm Fishes from the Late Devonian of North America. Records of the Australian Museum, 55 (1): 45–60.
  4. 1 2 Ritchie, A., 1975: Groenlandaspis in Antarctica, Australia and Europe. Nature, 254: 569–573.
  5. ↑ GESS, R. W. & HILLER, N. A. (1995b). Preliminary catalogue of fossil algal, plant,arthropod, and fish remains from a Late Devonian black shale near Grahamstown,South Africa. In Annals of the Cape Provincial Museums (Natural History) (Volume 19),pp. 225–304. Cape Provincial Museums, Grahamstown, South Africa.
  6. ↑ Olive, S., Prestianni, C. & Dupret, V., 2015: A new species of Groenlandaspis Heintz, 1932 (Placodermi, Arthrodira), from the Famennian (Late Devonian) of Belgium. Journal of Vertebrate Paleontology, 35 (4): e935389. doi: 10.1080/02724634.2014.935389
  7. ↑ Janvier, P. and A. Ritchie. 1977. Le genre Groenlandaspis Heintz (Pisces,Placodermi, Arthrodira) dans le D6vonien d'Asie. Colloques Researches Academie des Sciences de Paris, series D, 284:1385-1388.
  8. 1 2 Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 32. ISBN   1-84028-152-9.
  9. 1 2 Gess, Robert W.; Whitfield, Alan K. (August 22, 2020). "Estuarine fish and tetrapod evolution: insights from a Late Devonian (Famennian) Gondwanan estuarine lake and a southern African Holocene equivalent". Biological Reviews. 95 (4): 865–888. doi:10.1111/brv.12590 – via Wiley Online Library.
  10. 1 2 3 4 Gess, Robert W. and Whitfield Alan K. (2020). "Estuarine fish and tetrapod evolution: Insights from a Late Devonian (Famennian) Gondwanan estuarine lake and a southern African Holocene equivalent". Biological Reviews. doi:10.1111/brv.12590. PMID   32059074
  11. 1 2 LONG, J.A., ANDERSON, M. E., GESS, R. W. & HILLER, N. (1997). New placoderm fishes from the Late Devonian of South Africa. Journal of Vertebrate Palaeontology 17, 253–268.)
  12. ↑ Coloring Fossils. Science. 15 Aug 1997: Vol. 277, Issue 5328, pp. 905. DOI: 10.1126/science.277.5328.905b.
  13. ↑ GESS, R. W. & HILLER, N. (1995a). Late Devonian charophytes from the Witteberg Group, South Africa. Review of Palaeobotany and Palynology 89, 417–428.
  14. ↑ LONG, J.A., ANDERSON, M. E., GESS, R. W. & HILLER, N. (1997). New placoderm fishes from the Late Devonian of South Africa. Journal of Vertebrate Palaeontology 17, 253–268.
  15. ↑ GESS, R. W. & TRINAJSTIC, K. M. (2017). New morphological information on, and species of placoderm fish Africanaspis (Arthrodira, Placodermi) from the Late Devonian of South Africa. PLoS One 12(4), e0173169.
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