Supriya Ghosh (Editor)

Sacabambaspis

Updated on
Edit
Like
Comment
Share on FacebookTweet on TwitterShare on LinkedInShare on Reddit
Kingdom
  
Order
  
†Arandaspidiformes

Phylum
  
Chordata

Class
  
Family
  
†Sacabambaspidae

Sacabambaspis Sacabambaspis janvieri Spinops

Genus
  
†SacabambaspisGagnier, Blieck & Rodrigo, 1986

Similar
  
Arandaspida, Astraspis, Arandaspis prionotolepis, Pteraspidomorphi, Heterostraci

Sacabambaspis is an extinct genus of jawless fish that lived in the Ordovician period. Sacabambaspis lived in shallow waters on the continental margins of Gondwana. It is the best known arandaspid with many specimens. It is related to Arandaspis.

Contents

Sacabambaspis sacabambaspis DeviantArt

Description

Sacabambaspis sacabambaspis DeviantArt

Sacabambaspis was 25 cm in length. The body shape of Sacabambaspis vaguely resembled that of a tadpole with an oversized head, flat body, wriggling tail, and lack of fins. It had characteristic, frontally positioned eyes, like car head lamps.

Armor

Sacabambaspis Chance discovery contributes to origins and evolution focus

Sacabambaspis had a head shield made from a large upper (dorsal) plate that rose to a slight ridge in the midline, and a deep curved lower (ventral) plate, this headshield is ornamented with characteristic oak-leaf shaped or tear-drop shaped tubercles. Also it had narrow branchial plates which link these two along the sides, and cover the gill area. The eyes were far forward and between them are possibly two small nostrils and they, which are surrounded by what is thought to be endoskeletal bone, and putative nostrils, are found at the extreme anterior of the head, one of the diagnostic features of the arandaspids. The rest of the body was covered by long, strap-like scales behind the head shield.

Tail

Sacabambaspis httpsuploadwikimediaorgwikipediacommonsthu

The tail consists of relatively large dorsal and ventral webs and an elongated notochordal lobe, the posterior end of which is bordered by a small fin web. This tail structure clearly differs from that of heterostracans, which are currently grouped with arandaspids and astraspids in the clade Pteraspidomorphi (Gagnier 1993, 1995; Donoghue & Smith 2001; Sansom et al. 2005), in which the caudal fin looks diphycercal (i.e. symmetrical) and strengthened by a few large radials (Janvier 1996).

Discovery and species

Genus named after the village of Sacabamba, Cochabamba Department, Bolivia, where the first examples were found.

Sacabambaspis Sacabambaspis Wikipedia

  • S. janvieri (Gagnier, Blieck & Rodrico, 1986), the type species, is known from Bolivia. There are 30 known specimens of this Bolivian species, all crammed into a very confined area, believed to be the result of a fish kill, probably due a sudden inflow of freshwater from a large storm. They were found associated with a large number of lingulid brachiopods, also killed at the same time.
  • S. sp. (Young, 1997), is known from Central Australia. Isolated scales found in the Horn Creek Siltstone from Central Australia have a very similar ornamentation to the Bolivian scales.
  • S. sp. (Albanesi & Astini, 2002), is known from Argentina.
  • S. sp.( Sansom et al., 2009), is known from Oman, Arabian Peninsula. The Oman discoveries showed that the fish were present all around the margins of the ancient continent of Gondwana and not just in the southern regions as had previously been shown by the findings from South America and Australia.
  • Feeding

    Sacabambaspis Arandaspida

    Although it had no jaws, the mouth of Sacabambaspis janvieri was lined with nearly 60 rows of small bony oral plates which were probably movable in order to provide more efficient suction-action through expansion and contraction of the oral cavity and pharynx.

    Sensory system

    The fossils of Sacabambaspis show clear evidence of a sensory structure (lateral line system). This is a line of pores within each of which are open nerve endings that can detect slight movements in the water, produced for example by predators. The arrangement of these organs in regular lines allows the fish to detect the direction and distance from which a disturbance in the water is coming.

    References

    Sacabambaspis Wikipedia


    Similar Topics