Notogoneus osculus

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Notogoneus osculus
Notogoneus osculus, Wyoming, USA, Early Eocene - Royal Ontario Museum - DSC00120.JPG

Notogoneus osculus

Temporal occurrence
early Eocene
53 to 42 million years
Locations
  • British Columbia
  • Colorado
  • Wyoming
Systematics
Cohort : Otomorpha
Sub-cohort : Ostariophysi
Order : Sandfish (Gonorynchiformes)
Family : Gonorynchidae
Genre : Notogoneus
Type : Notogoneus osculus
Scientific name
Notogoneus osculus
Cope , 1885

Notogoneus osculus ( Gr .: νῶτος back [fin], γωνιαῖος (simplified to goneus) [three] angular, Latin : osculum = little mouth) was an Eocene freshwater fish in North America. Because it was found in lakes with a thick layer of digested sludge ( Fossil Butte Member of the Green River Formation ), it is one of the best traditional forms of its time. From the genus Notogoneus ( Upper Cretaceous to Upper Oligocene ) about eight other species have been described in Europe, Asia, North America and Australia. It isclosely relatedto the recent genus Gonorynchus , so that one understands its "retreat" into the sea: the Notogoneus species in fresh water had togive wayto the related but more developed carp-like species (among others).

description

Notogoneus differs from Gonorynchus (food: small crustaceans such as Harpacticoida, etc.) by having a more plump shape. The mouth is larger and its fins are not moved toward the tail, that allowed him no pike-like quick start. Both belong to the Gonorynchidae , which existed with † Charitosomus , † Chanopsis , † Judeichthys and † Ramallichthys since the Middle Cretaceous ( Cenomanium ). With the Otophysi , whose most original forms are the carp-like (Cypriniformes), the Gonorynchiformes share the alarm reaction to the terrible substance stored in the skin (they are more or less sociable) and the toothlessness of the jaws. Teeth for crushing are in the middle of the throat (as in the Gonorynchidae) but less favorable than at the entrance to the esophagus (e.g. in the Cyprinidae), so that as little as possible is lost through the gill slits. The carp fish are stomachless, which is seen as an adaptation to mollusc food; the gonorynchids have not passed through such a "stage" ( pyloric tubes and stomach are correlated). The development of Weber's apparatus is still unclear , to which there are certain "hints" in the Gonorynchidae - Notogoneus probably had a swim bladder ( Gonorynchus may have given it up in the sea), which he perhaps even like his relatives Chanos , Kneria and Phractolaemus for air breathing may have used, because he lived in waters that were sometimes low in oxygen .

The structure of the skull is very similar to Gonorynchus (Ridewood 1905; Gregory 1933). Unfortunately, there is no functional analysis of the latter, so that the strong reduction in premaxillaries (in both) remains unclear - something like this is not known from other benthic eaters. (There are certain functional similarities to Zoarces americanus .) The maxillae and lower jaw are large, but the mouth itself was small, arched, which speaks for powerful sucking for food. The suboperculum is very enlarged (lobed at the back; also in Gonorynchus the Branchiostegalmembran - with four radii in both genera - is still quite large and attached to the " isthmus "). The interoperculum is long and large, the dental angled opposite the articular. Perkins (1970) suspects a small A ω on the dental bone - although this muscle does not appear in any recent gonorynchiforms - for reasons that are not clear - it cannot, however, be ruled out based on experience with cyprinids (in which it is usually but not always absent).

relationship

Of the synapomorphies of the Gonorynchiformes that Wiley and Johnson (2010) list, one can recognize the following in Notogoneus :

  1. Interorbital septum largely reduced (eyes large, skull very narrow in front, mesethmoid and nasals as in the gonorynchus very small, nasal capsules without side wall; olfactory nerve emerges through the frontal (!); Pterosphenoids small and widely separated; base phenoid and orbitosphenoid are absent; the parasphenoid wings extend far to the sphenoticum up).
  2. Parietals small, widely separated (lateroparietal; in gonorynchus very small; frontals very large, square, with narrow supraorbital processes; brain skulls wide and low). The frontalia are not fused (as previously suspected).
  3. Jockstrap stretched (pine kurz.- Metapterygoid weak - at Gonorynchus almost only band-like - something very unusual!). Palatinum in front of the prefrontal reaches far forward into the rostrum, the maxillary is guided by it.
  4. Epicentralia ( bones ) present, three series (including “head ribs”; Patterson & Johnson 1995); by T. Monod (1963) as "dorsal ribs" (as the sharks have). (With Notogoneus fossil traces clearly.)
  5. Epibranchial organ present - can also be assumed for Notogoneus , as plesiomorphic and functionally still important. See Musculature in Springer & Johnson (2004).
  6. First neural arch enlarged, syndesmotically connected with the supraoccipital and exoccipital. (Developed further by Otophysi as part of Weber's apparatus.) Basioccipital with articulated head for the first vertebra (Ridewood 1905) - would be something very unusual again.
  7. Pharyngealia inferiora (“lower pharyngeal jaw”, Ceratobranchiale V) toothless (otherwise very rare in Teleostei: Gyrinocheilus ). ( Tooth plates in † Charitosomus , † Notogoneus and Gonorynchus merely entopterygoid-basibranchial: pinched teeth.)
  8. Ligamentum Baudeloti (a ligament between the exoccipital and shoulder girdle [Supracleithrum], which limits its lateral movement; unimportant in meiophages (small animal eaters), therefore not present (Patterson & Johnson 1995)).
  9. Foremost rib (on the third vertebra) significantly wider than the following. (In total, Notogoneus had 35 pairs of ribs.)

(Features 10 and 11 relate to the esophagus (gullet) and are therefore lost for Notogoneus .)

12. Second uroneural elongated rostroventrally. (Tail skeleton: central element consists of pu1 + u1 + u2 + un1, so it is less concentrated than in gonorynchus .)

It is unlikely that Notogoneus owned a Bartel (the mouth is less underdeveloped and larger than that of Gonorynchus ). The fin formula D (I /) 13-15, A 9-10, P 14-15, V 8, C 19-20 corresponds well with that of Gonorynchus . 50 or 51 vertebrae ( Gonorynchus : 54 or 55). Scales small (about two per myotome ; in gonorynchus only every third one is pierced on the lateral line ). As with gonorynchus , the head was covered with elongated scales with velvet-like thorns on the back (ie, ctenoid scales of a special kind). Notogoneus osculus reached 60 cm in length - like the largest gonorynchus species ( G. gonorynchus ). The caudal fin is only slightly incised at the back.

ecology

Fossil in the Utah Museum of Natural History , Salt Lake City .

Most of the fish come from the sediment of Lower Oocene Fossil Lake in southwest Wyoming . The old sediment surface even shows signs of swimming, traces of food and snapping, which can most likely be attributed to Notogoneus . The food consisted of softer sediment dwellers ( oligochaetes , crabs, insect larvae that could be crushed with the "inner bite", perhaps also thin-shelled molluscs, algae and parts of plants). Spawning possibly took place in tributaries (there are no fossils of young animals in the lake sediment, not even near the shore). In Fossil Lake, which existed for millions of years, Notogoneus also brought herring relatives ( Knightia and Diplomystus ), suckers , catfish , a pike ( Esox ), Percopsidae , Asineopidae and early perch , as well as the smell of fresh water , paddlefish , bone pike , Amiidae , bonsai and moon- eyed fish in front.

literature

  • Emmanuel Fara, Mireille Gayet et Louis Taverne: Les Gonorynchiformes fossiles: distribution et diversité. In: Cybium 31, 2007, pp. 115-122.
  • Lance Grande, Terry Grande: Redescription of the type species for the genus † Notogoneus (Teleostei: Gonorynchidae) based on new, well-preserved material. In: Journal of Paleontology. 82, 2008, pp. 1-31. doi : 10.1666 / 0022-3360 (2008) 82 [1: ROTTSF] 2.0.CO; 2
  • Philip L. Perkins: Notogoneus osculus Cope, an Eocene fish from Wyoming (Gonorynchiformes, Gonorynchidae). Postilla (Peabody Museum, Yale Univ.) 147, 1970, 18 pp.

Individual evidence

  1. ^ The Geologic History of Fossil Butte National Monument and Fossil Basin NPS Occasional Paper No. 3. Archived from the original on July 29, 2014 ; accessed on January 13, 2015 .
  2. ^ WK Gregory (1933): Fish skulls. Fish skulls; a study of the evolution of natural mechanisms (p. 175-178)
  3. ^ Gordon J. Howes: Cranial muscles of gonorynchiform fishes, with comments on generic relationships. In: Bull. Br. Mus. Nat. Hist. (Zool.) 49, 1985, pp. 213-303.
  4. ^ EO Wiley, G. David Johnson: A teleost classification based on monophyletic groups. In: Joseph S. Nelson, Hans-Peter Schultze, Mark VH Wilson: Origin and Phylogenetic Interrelationships of Teleosts. 2010, Verlag Dr. Friedrich Pfeil, Munich, ISBN 978-3-89937-107-9 .
  5. ↑ Fink, SV & Fink, WL (1981): Interrelationships of ostariophysan fi shes. - Zool. J. Linn. Soc. 72: 297-353.
  6. ↑ a b c d Fink, SV & Fink, WL (1996): Interrelationships of ostariophysan fi shes (Teleostei). - In: Stiassny, MLJ, Parenti, LR & Johnson, GD (eds.): Interrelationships of Fishes: 405-426; San Diego (Academic Press).
  7. ^ VG Springer, GD Johnson: Study of the dorsal gill-arch musculature of teleostome fishes, with special reference to the Actinopterygii. In: Bull. Biol. Soc. Wash. 11, 2004, pp. 1-236.
  8. ^ C. Patterson, GD Johnson: The intermuscular bones and ligaments of teleostean fishes. In: Smithsonian contributions to zoology 559, 1995, pp. 1–83.
  9. ^ AJ Martin, GM Vazquez-Prokopec, M. Page: First known feeding trace of the eocene bottom-dwelling fish Notogoneus osculus and its paleontological significance. In: PloS one. Volume 5, number 5, 2010, ISSN  1932-6203 , p. E10420, doi : 10.1371 / journal.pone.0010420 . PMID 20463969 . PMC 2864752 (free full text).
  10. ^ Gregg F. Gunnell (ed.): Eocene biodiversity: Unusual occurrences and rarely sampled habitats. (Topics in Geobiology, Volume 18), 2001 ( limited preview in Google Book Search)

Remarks

  1. ↑ The Gonorynchiformes as Anotophysi are the primitive sister group to the Otophysi ; Fink and Fink 1981.
  2. ↑ Having no teeth can be beneficial when eating small amounts of food.
  3. ↑ The consideration is not compelling, because there are quite a few air breathers in the other Otophysi orders, but especially none in the Cypriniformes - they rather have physiological adaptations to a lack of oxygen, e.g. B. the tench ( Tinca tinca ).
  4. ↑ Y. le Danois (1966) found it in Gonorynchus and even in “labial muscles”, which Perkins also quotes - but that is pure fantasy, for which this author was known.