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St Bathans fauna

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Palaeontologists sieving St Bathans fossils in the Manuherikia River

The St Bathans fauna is found in the lower Bannockburn Formation of the Manuherikia Group of Central Otago, in the South Island of New Zealand. It comprises a suite of fossilised prehistoric animals from the late Early Miocene (Altonian) period, with an age range of 19–16 million years ago.

The layer in which the fossils are found derives from littoral zone sediments deposited in a shallow, freshwater lake, with an area of 5600 km2 from present day Central Otago to Bannockburn and the Nevis Valley in the west; to Naseby in the east; and from the Waitaki Valley in the north to Ranfurly in the south. The lake was bordered by an extensive floodplain containing herbaceous and grassy wetland habitats with peat-forming swamp–woodland.[1] At that time the climate was warm with a distinctly subtropical Australian climate[2] and the surrounding vegetation was characterised by casuarinas, eucalypts and palms as well as podocarps, araucarias and southern beeches.

The fossiliferous layer has been exposed at places along the Manuherikia River and at other sites in the vicinity of the historic gold mining town of St Bathans. The fauna consists of a variety of vertebrates, including fish, a crocodilian, a rhynchocephalian (a relative of tuatara),[3] geckos,[4] skinks,[4] a primitive mammal,[5] several species of bats,[6] and several kinds of birds, especially waterbirds.[7] Of tree-dwelling birds, parrots outnumber pigeons thirty to one.[8] Proapteryx, a basal form of kiwi, is known from there. The Miocene ecosystem was recovering from the ‘Oligocene drowning’ a few million years earlier, when up to 80% of the current land area of New Zealand was submerged. The wildlife that lived in, on, and around the palaeolake Manuherikia was uniquely New Zealand, which strongly suggesting that some emergent land remained during this near drowning event.[9] Marked global cooling and drying during the Miocene, Pliocene and the Pleistocene Ice Ages resulted in the extinction of the 'subtropical' elements of the St Bathans fauna. Those that survived adapted to the dynamic geological and climatic changes, and would form part of the enigmatic fauna that characterised New Zealand when humans arrived in the late 13th century.[10]

History of excavation

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Quarrying bed HH1a, Bannockburn Formation, for the early Miocene St Bathans Fauna

Research on the St Bathans fauna is led by Trevor Worthy, a New Zealander based in Flinders University, Adelaide. Other key scientists involved include Jenny Worthy from Flinders University, Paul Scofield and Vanesa De Pietri from Canterbury Museum, and Alan Tennyson from the Museum of New Zealand Te Papa Tongarewa.[11] In 2016 Vanesa De Pietri was awarded a Royal Society of New Zealand Marsden Fast Start grant to study the shorebird fossils.[12] This long-running (since 2000) collaborative research programme also includes scientists from the University of New South Wales in Sydney and from the University of Queensland in Brisbane.[10]

Mammals

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Surprisingly, given modern New Zealand's dearth of land mammals, there is a basal theriiform mammal, the St Bathans mammal.[5] Several species of mystacine bats are also known, as well as a vesper bat and several incertae sedis species.[6][13] This bat fauna included Vulcanops, a giant burrowing bat three times the size of today’s relatives, and more closely related to South American bats.[14] This suggests that small land mammals were a common component of New Zealand's fauna in the Miocene, with even bats being significantly more diverse than today.

Birds

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New Zealand's two modern palaeognath clades, the kiwi and moa, have early representatives in the fauna. The former is represented by the diminutive, possibly volant Proapteryx.[15] The latter is represented by several bones and egg shells of currently unnamed species, but already identifiable as true moa, being large sized and flightless.[16] The fact that moa are already recognisably modern in anatomy, and possibly ecology, while kiwis are fairly unspecialised and probably still flighted, confirms the previous suspicions that neither clade is closely related and that they arrived in New Zealand independently: moa arrived and became flightless earlier in the Cenozoic, while kiwi were then recent arrivals.[15]

Anseriforms (waterfowl) dominate the fauna. At least nine species are recognised from St Bathans, making it the richest waterfowl fauna in the world.[9] All the waterfowl species are unique to New Zealand. Bones attributable to Cape Barren goose (Cereopsis spp.), thought to represent the ancestors of extinct Pleistocene-Holocene Cnemiornis goose, and those of a second possible goose species have been found.[17] In both instances, there is not enough material currently to erect species.[17] Stiff-tailed ducks dominate the fauna with Manuherikia lacustrina, M. minuta, M. douglasi, Dunstanneta johnstoneorum and a further undescribed species of Manuherikia.[1][18][9] One species of shelduck, Miotadorna sanctibathansi, has been found and is common.[1] The dabbling duck Matanas enrightii remains poorly known as only a few fossils have been found.[1]

Palaelodids are ancient relatives of flamingos. The new species from St Bathans (Palaelodus aotearoa) is smaller than, and morphologically distinct from, the Late Oligocene-Early Miocene Palaelodus wilsoni from Australia.[19]

Two pigeon species have been described. Rupephaps is a large fruit pigeon, possibly related to the modern Hemiphaga species. The Zealandian dove is similar to the Nicobar pigeon.[8]

Several Gruiformes have been described. The St Bathans adzebill (Aptornis proasciarostratus) was only slightly smaller than its more recent descendants.[20] There were two flightless rails: the common Priscaweka parvales and uncommon Litorallus livezeyi. Priscaweka parvales was no bigger than a sparrow.[21]

Charadriiformes, including gulls, terns, noddies, snipes, dotterels, plovers, jacanas, oystercatchers, sheathbills and the plains-wanderer, are a large group of birds that are mostly found in marine or semi-marine environments. There are about 350 species, and they are mostly small to medium-sized. Two of these are known from St Bathans, the New Zealand lake-wanderer (Hakawai melvillei), a relative of the plains-wanderer, and Sansom's plover (Neilus sansomae), a plover-like bird of uncertain affinities but possibly related to sheathbills and the Magellanic plover.

Petrels are seabirds in the order Procellariformes. This group includes albatrosses. Petrels today make up most of all species of seabird, and the order is the only order of birds to be entirely marine. One species of petrel is known from the St Bathans Fauna – a diving petrel in the same genus as modern diving petrels, the Miocene diving petrel (Pelecanoides miokuaka).

At least two herons are known: Pikaihao bartlei and Matuku otagoense. The former is a bittern, while the latter is a much larger species that appears to be basal within Ardeidae (the herons).[7]

One eagle, similar in size to a wedge-tailed eagle, and another bird of prey, similar in size to a small hawk, have been found, but await formal description.[9]

Two parrot genera are represented. Heracles is represented by its sole species, Heracles inexpectatus, the largest known parrot, weighing 7 kilograms and standing 1 meter tall. Nelepsittacus is represented by at least four species. These vary drastically in size, suggesting that they occupied a wide variety of ecological niches, having diversified in the relative absence of other parrots.[22]

A New Zealand wren, Kuiornis indicator, is known from these deposits, possibly similar to the modern rifleman.[23] Two or three other passerine species remain undescribed.

Herpetofauna (amphibians and reptiles)

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The St Bathans fauna is rich in reptile and amphibian remains. Several groups present in modern New Zealand are represented, such as leiopelmatid frogs,[24] a sphenodontian similar to the modern tuatara,[3] geckos, and skinks.[4] However, there are also several species not seen in modern-day New Zealand, such as a mekosuchine crocodile up to 3 metres in length[25] and pleurodire and meiolaniid turtles.[26] This suggests that New Zealand's herpetofauna was much richer in this epoch, probably because its climate was considerably warmer than today.[26]

Fish

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The vast majority of the bones excavated from St Bathans are those of freshwater fish such as the ancient relatives of today's bullies, galaxiids, and the extinct New Zealand grayling.[27]

Aquatic invertebrates

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As well as fishes, shellfish, including freshwater mussels, and freshwater crayfish dominated the aquatic life in the palaeolake Manuherikia.[10] A new species of St Bathans freshwater limpet, Latia manuherikia, was described by malacologist Bruce Marshall in 2011. This was both the first known fossil Latia and the first record of this genus from the South Island.[28]

Absent taxa

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Notable examples of absent taxa include marsupials, snakes, agamid and varanid lizards, lungfish, eels, cockatoos, and all but one lineage (bellbirds and tūī) of the 80 species of Australian honeyeaters.[10]

References

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  1. ^ a b c d Worthy, Trevor H.; Tennyson, Alan J. D.; Jones, C.; McNamara, J. A.; Douglas, B. J. (2007). "Miocene waterfowl and other birds from central Otago, New Zealand". Journal of Systematic Palaeontology. 5 (1): 1–39. Bibcode:2007JSPal...5....1W. doi:10.1017/S1477201906001957. hdl:2440/43360. ISSN 1477-2019. S2CID 85230857.
  2. ^ Worthy, Trevor (Jan–Feb 2011). "Deep secrets". New Zealand Geographic. Retrieved 2019-11-15.
  3. ^ a b Jones MEH; Tennyson AJD; Worthy JP; Evans SE; Worthy TH (2009). "A sphenodontine (Rhynchocephalia) from the Miocene of New Zealand and palaeobiogeography of the tuatara (Sphenodon)". Proceedings of the Royal Society B. 276 (1660): 1385–1390. doi:10.1098/rspb.2008.1785. PMC 2660973. PMID 19203920.
  4. ^ a b c Lee Michael S. Y.; Hutchinson Mark N.; Worthy Trevor H.; Archer Michael; Tennyson Alan J. D.; Worthy Jennifer P.; Scofield R. Paul (2009-12-23). "Miocene skinks and geckos reveal long-term conservatism of New Zealand's lizard fauna". Biology Letters. 5 (6): 833–837. doi:10.1098/rsbl.2009.0440. PMC 2827994. PMID 19656857.
  5. ^ a b Worthy, Trevor H.; Tennyson, Alan J. D.; Archer, Michael; Musser, A. M.; Hand, S. J.; Jones, C.; Douglas, B. J.; McNamara, J. A.; Beck, R. M. D. (2006). "Miocene mammal reveals a Mesozoic ghost lineage on insular New Zealand, southwest Pacific". Proceedings of the National Academy of Sciences. 103 (51): 19419–19423. Bibcode:2006PNAS..10319419W. doi:10.1073/pnas.0605684103. ISSN 0027-8424. PMC 1697831. PMID 17159151.
  6. ^ a b Hand, SJ; Worthy, Trevor H.; Archer, M; Worthy, JP; Tennyson, AJD; Scofield, RP (2013). "Miocene mystacinids (Chiroptera, Noctilionoidea) indicate a long history for endemic bats in New Zealand". Journal of Vertebrate Paleontology. 33 (6): 1442–1448. Bibcode:2013JVPal..33.1442H. doi:10.1080/02724634.2013.775950. S2CID 85925160.
  7. ^ a b Scofield, R. Paul; Worthy, Trevor H. & Tennyson, Alan J.D. (2010). "A heron (Aves: Ardeidae) from the Early Miocene St Bathans Fauna of southern New Zealand". In W.E. Boles & T.H. Worthy. (eds.). Proceedings of the VII International Meeting of the Society of Avian Paleontology and Evolution. Vol. 62. pp. 89–104. doi:10.3853/j.0067-1975.62.2010.1542. {{cite book}}: |journal= ignored (help)
  8. ^ a b Guildford, Jonathan (8 May 2018). "Newly-discovered pigeon species related to the dodo lived in NZ millions of years ago". Stuff. Retrieved 8 May 2018.
  9. ^ a b c d Worthy, Trevor H.; Pietri, Vanesa L. De; Scofield, R. Paul (2017-07-03). "Recent advances in avian palaeobiology in New Zealand with implications for understanding New Zealand's geological, climatic and evolutionary histories". New Zealand Journal of Zoology. 44 (3): 177–211. doi:10.1080/03014223.2017.1307235. ISSN 0301-4223. S2CID 90635192.
  10. ^ a b c d Rawlence, Nic (19 March 2018). "Through the looking glass: Fossils reveal a Miocene Wonderland at St Bathans". Sciblogs. Retrieved 2019-04-28.
  11. ^ "Bone Hunters: The ancient lake revealing New Zealand's mysterious past". 25 June 2023.
  12. ^ "Marsden Fund Update" (PDF). Royalsociety.org.nz. 2016. Retrieved 2022-03-28.
  13. ^ Hand, Suzanne J.; Lee, Daphne E.; Worthy, Trevor H.; Archer, Michael; Worthy, Jennifer P.; Tennyson, Alan J. D.; Salisbury, Steven W.; Scofield, R. Paul; Mildenhall, Dallas C. (2015). "Miocene Fossils Reveal Ancient Roots for New Zealand's Endemic Mystacina (Chiroptera) and its Rainforest Habitat". PLOS ONE. 10 (6): e0128871. Bibcode:2015PLoSO..1028871H. doi:10.1371/journal.pone.0128871. ISSN 1932-6203. PMC 4470663. PMID 26083758.
  14. ^ Worthy, Trevor H.; Salisbury, Steven W.; Pietri, Vanesa L. De; Tennyson, Alan J. D.; R. Paul Scofield; Gunnell, Gregg F.; Simmons, Nancy B.; Archer, Michael; Beck, Robin M. D. (2018-01-10). "A new, large-bodied omnivorous bat (Noctilionoidea: Mystacinidae) reveals lost morphological and ecological diversity since the Miocene in New Zealand". Scientific Reports. 8 (1): 235. Bibcode:2018NatSR...8..235H. doi:10.1038/s41598-017-18403-w. ISSN 2045-2322. PMC 5762892. PMID 29321543.
  15. ^ a b Scofield, R. Paul; Hand, Suzanne J.; Salisbury, Steven W.; Tennyson, Alan J. D.; Worthy, Jennifer P.; Worthy, Trevor (2013). "Miocene fossils show that kiwi (Apteryx, Apterygidae) are probably not phyletic dwarves". Paleornithological Research 2013 – Proceedings of the 8th International Meeting of the Society of Avian Paleontology and Evolution: 63–80. ISBN 978-3-902421-82-1.
  16. ^ Tennyson, Alan J.D.; Worthy, Trevor H.; Jones, Craig M.; Scofield, R. Paul; Hand, Suzanne J. (2010). "Moa's Ark: Miocene fossils reveal the great antiquity of moa (Aves: Dinornithiformes) in Zealandia". Records of the Australian Museum. 62 (1): 105–114. doi:10.3853/j.0067-1975.62.2010.1546.
  17. ^ a b Worthy, Trevor H.; Tennyson, Alan J. D.; Hand, Suzanne J.; Scofield, R. Paul (2008-06-01). "A new species of the diving duck Manuherikia and evidence for geese (Aves: Anatidae: Anserinae) in the St Bathans Fauna (Early Miocene), New Zealand". Journal of the Royal Society of New Zealand. 38 (2): 97–114. Bibcode:2008JRSNZ..38...97W. doi:10.1080/03014220809510549. ISSN 0303-6758. S2CID 84743704.
  18. ^ Worthy, Trevor H.; Lee, Michael S. Y. (2008). "Affinities of Miocene Waterfowl (anatidae: Manuherikia, Dunstanetta and Miotadorna) from the St Bathans Fauna, New Zealand". Palaeontology. 51 (3): 677–708. Bibcode:2008Palgy..51..677W. doi:10.1111/j.1475-4983.2008.00778.x. ISSN 1475-4983.
  19. ^ Worthy, Trevor H.; Tennyson, Alan J. D.; Archer, Michael; Scofield, R. Paul (2010). Boles, Walter E.; Worthy, Trevor H. (eds.). "First record of Palaelodus (Aves: Phoenicopteriformes) from New Zealand. In Proceedings of the VII International Meeting of the Society of Avian Paleontology and Evolution, ed. W.E. Boles and T.H. Worthy". Records of the Australian Museum. 62 (1): 77–88. doi:10.3853/j.0067-1975.62.2010.1545. ISSN 0067-1975.
  20. ^ Worthy, Trevor H.; Tennyson, Alan J. D.; Scofield, R. Paul (2011-07-01). "Fossils reveal an early Miocene presence of the aberrant gruiform Aves: Aptornithidae in New Zealand". Journal of Ornithology. 152 (3): 669–680. doi:10.1007/s10336-011-0649-6. ISSN 1439-0361. S2CID 37555861.
  21. ^ Mather, Ellen K.; Tennyson, Alan J. D.; Scofield, R. Paul; Pietri, Vanesa L. De; Hand, Suzanne J.; Archer, Michael; Handley, Warren D.; Worthy, Trevor H. (2019-03-04). "Flightless rails (Aves: Rallidae) from the early Miocene St Bathans Fauna, Otago, New Zealand". Journal of Systematic Palaeontology. 17 (5): 423–449. Bibcode:2019JSPal..17..423M. doi:10.1080/14772019.2018.1432710. ISSN 1477-2019. S2CID 90809776.
  22. ^ Worthy, Trevor H.; Tennyson, Alan J. D.; Scofield, R. Paul (2011). "An early Miocene diversity of parrots (Aves, Strigopidae, Nestorinae) from New Zealand". Journal of Vertebrate Paleontology. 31 (5): 1102–1116. Bibcode:2011JVPal..31.1102W. doi:10.1080/02724634.2011.595857. ISSN 0272-4634. S2CID 86361015.
  23. ^ Archer, Michael; Boles, Walter E.; Scofield, R. Paul; Worthy, Jennifer P.; Tennyson, Alan J. D.; Nguyen, Jacqueline M. T.; Hand, Suzanne J.; Worthy, Trevor H. (2010). "Biogeographical and Phylogenetic Implications of an Early Miocene Wren (Aves: Passeriformes: Acanthisittidae) from New Zealand". Journal of Vertebrate Paleontology. 30 (2): 479–498. Bibcode:2010JVPal..30..479W. doi:10.1080/02724631003618033. ISSN 0272-4634. S2CID 85994536.
  24. ^ Worthy, T. H.; Tennyson, A. J. D.; Scofield, R. P.; Hand, S. J. (2013-12-01). "Early Miocene fossil frogs (Anura: Leiopelmatidae) from New Zealand". Journal of the Royal Society of New Zealand. 43 (4): 211–230. Bibcode:2013JRSNZ..43..211W. doi:10.1080/03036758.2013.825300. ISSN 0303-6758.
  25. ^ "The New Zealand fossil revolution". RNZ. 2017-11-07. Retrieved 2024-09-17.
  26. ^ a b Worthy, Trevor H.; Tennyson, Alan J. D.; Hand, Suzanne J.; Godthelp, Henk; Scofield, R. Paul (2011). "Terrestrial Turtle Fossils from New Zealand Refloat Moa's Ark". Copeia. 2011 (1): 72–76. doi:10.1643/CH-10-113. ISSN 0045-8511. S2CID 84241716.
  27. ^ Schwarzhans, Werner; Scofield, R. Paul; Tennyson, Alan J.D.; Worthy, Jennifer P.; Worthy, Trevor H. (2012). "Fish Remains, Mostly Otoliths, from the Non-Marine Early Miocene of Otago, New Zealand". Acta Palaeontologica Polonica. 57 (2): 319–350. doi:10.4202/app.2010.0127. hdl:2440/75818. ISSN 0567-7920.
  28. ^ Marshall, Bruce A. (2011). "A new species of Latia Gray, 1850 (Gastropoda: Pulmonata: Hygrophila: Chilinoidea: Latiidae) from Miocene Palaeo-lake Manuherikia, southern New Zealand, and biogeographic implications". Molluscan Research. 31: 47–52. doi:10.11646/mr.31.1.7.
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