Laccognathus embryi

Edit links
Source: Wikipedia, the free encyclopedia.

Laccognathus embryi
Temporal range:
Late Devonian
)
Reconstruction of Laccognathus embryi
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Sarcopterygii
Class: Porolepimorpha
Order: †Porolepiformes
Family: †Holoptychiidae
Genus: †Laccognathus
Species:
†L. embryi
Binomial name
†Laccognathus embryi
Downs et al., 2011
Discovery site of Laccognathus embryi

Laccognathus embryi is an

Late Devonian epoch (around 385.3 to 374.5 mya
).

Discovery

Specimens from at least 22 individuals of Laccognathus embryi were recovered from the

Tiktaalik roseae from the same locality.[2]

Ellesmere Island was also the site of previous

Norwegian scientific expeditions by the ship Fram in 1893-1896 by Fridtjof Nansen and in 1898–1902 by Otto Sverdrup. In the second expedition, a few vertebrate fossils were collected from Ellesmere Island by a member of Sverdrup's crew with the geologist Per Schei. The collection included a few porolepiform scales attributed to Glyptolepis and Holoptychius.[2]

Prior to its discovery, the genus Laccognathus was known only from Latvia and Russia. L. embryi is the first member of the genus discovered in North America.[2]

The fossil

sarcopterygian fish Laccognathus embryi of the Devonian was named in honour of Geologist Ashton F. Embry.[3]

Description

Comparison of an average adult human male, 170 cm (5.6 ft), with the approximate length of L. embryi, 1.8 m (6 ft).

Like other members of the genus, Laccognathus embryi possessed three deep longitudinal pits (fossae) on the external surface of the

water pressure, similar to the lateral line of modern fishes and sharks, an analogous to our ears.[4] It had a distinctly dorsoventrally flattened short and wide head, less than one-fifth of the length of the body and with a width-to-length ratio of approximately 2:1. The eyes were very small, even smaller than those of L. panderi. The jaws possessed coronoid fangs up to 3.8 cm (1.5 in) in length.[5] These were bordered with marginal teeth, with the exception of coronoids 1 and 2. Much of the external surface of the lower jaw is oriented downwards, suggesting that the animal spent a considerable amount of time resting on the substrate.[2]

L. embryi is estimated to have been 1.8 m (6 ft) long with a wide flattened body.

anal fins were positioned close to the caudal fin.[6] The body was also covered in broadly overlapping thick scales, each roughly 2.5 cm (1 in) in diameter and ornamented at the exposed ends with small radially arranged tubercles, ridges, or both.[2]

Distribution and geologic time range

Laccognathus embryi was recovered in the middle part of the Fram Formation, designated as the NV2K17

palynological examination reveals that the NV2K17 locality itself is from the early to middle Frasnian. The area is believed to have been the floodplain of a meandering river system.[2]

The variety of fossils found in Ellesmere Island is similar to those found in the

Laurussia) located at the equator during the Devonian period.[2]

Paleoecology

The flattened head of Laccognathus embryi indicates that it was a

estuarine deposits in Europe suggest that Laccognathus species could tolerate a wide range of environmental conditions and salinity levels.[2]

Taxonomy

Laccognathus embryi belongs to the genus Laccognathus, of the family

Dipnomorpha. Unlike its sister group, the Tetrapodomorpha, dipnomorphs were not direct ancestors of land vertebrates.[6]

The

Greek λάκκος (lakkos, 'pit') and γνάθος (gnathos, 'jaw') in reference to the three wide pits along the labial surface of the lower jaw. The specific name is in honour of Ashton Embry of the Geological Survey of Canada.[2]

See also

References

  1. ^ Tom Avril (September 18, 2011). "Arctic fish fossil quite a find". Pittsburgh Post-Gazette. Retrieved September 19, 2011.
  2. ^
    doi:10.1080/02724634.2011.599462
    .
  3. ^ "Ashton Embry". Geological Survey of Canada— Directory of Geoscience Expertise. Retrieved 30 December 2013.[permanent dead link]
  4. ^ Tom Avril (September 12, 2011). "Fish fossil sheds light on 'Euramerica' phase". The Inquirer. Retrieved September 15, 2011.
  5. ^ a b Christine Dell'Amore (September 12, 2011). "Ancient Toothy Fish Found in Arctic—Giant Prowled Rivers". National Geographic Daily News. Archived from the original on September 24, 2011. Retrieved September 13, 2011.
  6. ^
    doi:10.1134/S0031030106030129
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=Laccognathus_embryi&oldid=1186571317"