Sacabambaspis

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Sacabambaspis
Temporal range: Dapingian-Sandbian
Sacabambaspis janvieri cast (cropped).jpg
A cast (replica) of a Sacabambaspis janvieri fossil found in Bolivia. Displayed at the American Museum of Natural History, New York.
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Infraphylum: Agnatha
Class:† Pteraspidomorpha
Family:† Sacabambaspidae
Genus:† Sacabambaspis
Gagnier, Blieck & Rodrigo, 1986
Type species
† Sacabambaspis janvieri
Gagnier, Blieck & Rodrigo, 1986
Species
  • S. janvieriGagnier, Blieck & Rodrico, 1986

Sacabambaspis is an extinct genus of armored jawless fish which lived in the Ordovician period. Sacabambaspis inhabited shallow waters on the continental margins of Gondwana, with the most complete specimens found in Bolivia. Armor fragments are also known found in Argentina, Australia, [1] and Oman. [2]

Contents

With many well-preserved specimens, Sacabambaspis is the best-known member of the subclass Arandaspida. Arandaspids were among the earliest members of the class Pteraspidomorpha, alongside a far more diverse group of jawless fish, the Silurian– Devonian heterostracans. [3]

History

Bolivian specimens

Specimens of Sacabambaspis at Musee d'Histoire Naturelle, Paris. Sacabambaspis janvieri many specimens.JPG
Specimens of Sacabambaspis at Musée d'Histoire Naturelle, Paris.

Sacabambaspis is named after the village of Sacabamba, Cochabamba Department, Bolivia, where the first fossils of the genus were found. [4] S. janvieri, the type species of the genus, is known from the Anzaldo Formation of Bolivia. [4]

Sacabambaspis janvieri was first described by Gagnier, Blieck & Rodrico (1986), based on a few armor fragments. [4] Further discoveries in the late 1980s and early 1990s greatly expanded the list of specimens. [5] [6] [7] [8] [9] [10] [11] Later studies in the mid-2000s cleared up a few remaining points of ambiguity regarding its armor structure and tail anatomy. [12] [13]

Over 30 specimens have been found in Bolivia, all crammed into a very confined area. Their close arrangement is believed to be the result of a fish kill, probably due a sudden inflow of fresh water and sediments from a large storm. They were found associated with a large number of lingulid brachiopods, also killed at the same time. [14] [15] [16]

In June 2023, Sacabambaspis became a source of internet memes and fan art, following a viral tweet from August 2022 which celebrated a Sacabambaspis model on exhibit at the Natural History Museum of Helsinki in Finland. [17]

Other specimens

Indeterminate specimens (described as "Sacabambaspis sp.") have been found in many countries corresponding to the margin of Gondwana. Young (1997) described fossils of the genus from the Stokes Siltstone and Carmichael Sandstone of Central Australia. [1] Specimens have also been reported from Argentina. [18] [2]

Sansom et al. (2009) described specimens from the Amdeh Formation of Oman on the Arabian Peninsula. The Oman discoveries showed that the fish were present all around the periphery 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. [2] [19]

Description

Life restoration Sacabambaspis.jpg
Life restoration

Sacabambaspis was approximately 25 cm (9+3⁄4 inches) in length. The body shape of Sacabambaspis vaguely resembled that of a tadpole with an oversized head, flat body, narrow tail, and lack of fins. It had characteristic, frontally positioned eyes, like car headlamps. [20]

Armor

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. [12] [21] [22] It also had narrow branchial plates which link these two along the sides, and cover the gill area. [21] The eyes were far forward. Between them were possibly two small nostrils surrounded by what is thought to be endoskeletal bone and putative nostrils found at the extreme anterior of the head, one of the diagnostic features of the arandaspids. [21] [22] The rest of the body was covered by long, strap-like scales behind the head. [21]

Tail

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 Pteraspidomorpha (Gagnier 1993, 1995; Donoghue & Smith 2001; Sansom et al. 2005), in which the caudal fin looks diphycercal (i.e., symmetrical) and is strengthened by a few large radials (Janvier 1996). [13]

Paleobiology

Feeding

Although it was jawless, 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 feeding through expansion and contraction of the oral cavity and pharynx. [16]

Sensory system

The fossils of Sacabambaspis show clear evidence of a sensory structure (lateral line system). This is a line of canal 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. [22]

See also

References

  1. 1 2 Young, G. C. (1997-04-16). "Ordovician microvertebrate remains from the Amadeus Basin, central Australia". Journal of Vertebrate Paleontology. 17 (1): 1–25. Bibcode:1997JVPal..17....1Y. doi:10.1080/02724634.1997.10010948. ISSN   0272-4634.
  2. 1 2 3 Sansom, Ivan J.; Miller, C. Giles; Heward, Alan; Davies, Neil S.; Booth, Graham A.; Fortey, Richard A.; Paris, Florentin (2009). "Ordovician Fish from the Arabian Peninsula". Palaeontology. 52 (2): 337–342. Bibcode:2009Palgy..52..337S. doi: 10.1111/j.1475-4983.2009.00846.x . S2CID   128704925.
  3. ↑ Randle, Emma; Keating, Joseph N.; Sansom, Robert S. (2025). "A phylogeny for Heterostraci (stem‐gnathostomes)". Papers in Palaeontology. 11 (5). doi:10.1002/spp2.70030. ISSN   2056-2799.
  4. 1 2 3 Gagnier, Pierre-Yves; Blieck, Alain R. M.; S., Gabriela Rodrigo (1986). "First Ordovician vertebrate from South America" . Geobios. 19 (5): 629–634. Bibcode:1986Geobi..19..629G. doi:10.1016/S0016-6995(86)80058-4. ISSN   0016-6995.
  5. ↑ Gagnier, P.-Y. (1989). "The oldest vertebrate: a 470-million-year-old jawless fish, Sacabambaspis janvieri, from the Ordovician of Bolivia". National Geographic Research. 5: 250–253.
  6. ↑ Blieck, Alain; Elliott, David K.; Gagnier, Pierre-Yves (1991). "Some questions concerning the phylogenetic relationships of heterostracans, Ordovician to Devonian jawless vertebrates". In Chang, M.M.; Liu, Y.H.; Zhang, G.R. (eds.). Early vertebrates and related problems of evolutionary biology. Beijing, China: Science Press. pp. 1–17.
  7. ↑ Gagnier, P.-Y. (1992). "Ordovician vertebrates from Bolivia". Fosiles y facies de Bolivia. I. Vertebrados. Revista Tecnica de YPFB. 12: 371–379.
  8. ↑ Gagnier, Pierre-Yves; Blieck, Alain (1992). "On Sacabambaspis janvieri and the vertebrate diversity in Ordovician seas" (PDF). In Mark-Kurik, Elga (ed.). Fossil fishes as living animals. Academia. Vol. 1. Tallinn: Academy of Sciences of Estonia. pp. 9–20. ISBN   5-7976-0409-4.
  9. ↑ Gagnier, P.-Y. (1993). "Sacabambaspis janvieri, Vertébré ordovicien de Bolivie. I: Analyse morphologique". Annales de Paleontologie. 79 (1): 19–69.
  10. ↑ Gagnier, P.-Y. (1993). "Sacabambaspis janvieri, Vertébré ordovicien de Bolivie. II: Analyse phylogénétique". Annales de Paleontologie. 79: 119–166.
  11. ↑ Gagnier, Pierre-Yves (1995). "Ordovician Vertebrates and Agnathan phylogeny". Bulletin du Muséum national d'histoire naturelle. 17: 1–37.
  12. 1 2 Sansom, Ivan J; Donoghue, Philip C.J; Albanesi, Guillermo (2005-07-18). "Histology and affinity of the earliest armoured vertebrate". Biology Letters. 1 (4): 446–449. doi:10.1098/rsbl.2005.0349. PMC   1626355 . PMID   17148229.
  13. 1 2 Pradel, A.; Sansom, I. J.; Gagnier, P. Y.; Cespedes, R.; Janvier, P. (2006). "The tail of the Ordovician fish Sacabambaspis". Biology Letters. 3 (1): 72–75. doi:10.1098/rsbl.2006.0557. PMC   2373808 . PMID   17443969.
  14. ↑ Gagnier, P. Y.; Blieck, A.; Emig, C. C.; Sempere, T.; Vachard, D.; Vanguestaine, M. (1996-09-01). "New paleontological and geological data on the Ordovician and Silurian of Bolivia". Journal of South American Earth Sciences. 9 (5): 329–347. doi:10.1016/S0895-9811(96)00018-1. ISSN   0895-9811.
  15. ↑ Davies, Neil S.; Sansom, Ivan J.; Albanesi, Guillermo L.; Cespedes, Ricardo (2007-06-11). "Ichnology, palaeoecology and taphonomy of a Gondwanan early vertebrate habitat: Insights from the Ordovician Anzaldo Formation, Bolivia". Palaeogeography, Palaeoclimatology, Palaeoecology. 249 (1): 18–35. doi:10.1016/j.palaeo.2007.01.003. ISSN   0031-0182.
  16. 1 2 "Australia: The Land Where Time Began" . Retrieved 28 October 2013.
  17. ↑ Amber V (16 June 2023). "470-million-year-old fish Sacabambaspis goes viral in Japan, Among Us dev joins in on fun". Automaton Media. Retrieved 8 February 2024.
  18. ↑ Albanesi, G.L.; Benedetto, J.L.; Gagnier, P.-Y. (1993). "Sacabambaspis janvieri (Vertebrata) y conodontes del Llandeiliano temprano en la Formacion La Cantera, Precordillera de San Juan, Argentina". Boletin de la Academia Nacional de Ciencias. 60. Córdoba, Argentina: 519–543.
  19. ↑ Miller, George (24 June 2011). "How can something that small appear on TV?". NaturePlus. Archived from the original on 7 October 2018. Retrieved 28 October 2013.
  20. ↑ Janvier, Philippe (1997) Arandaspida The Tree of Life Web Project.
  21. 1 2 3 4 Benton, Michael J. (2005). Vertebrate Palaeontology 3rd Edition. Blackwell Publishing. p. 47. ISBN   978-1-4051-4449-0.
  22. 1 2 3 Samson, Ivan J.; Smith, Moya M.; Smith, Paul M. (2001-02-15). "The Ordovician radiation of vertebrates". In Ahlberg, Per Erik (ed.). Major Events in Early Vertebrate Evolution. CRC Press. pp. 156–171. doi:10.1201/b12434. ISBN   978-1-134-56886-4.
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