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Osteology Supports a Stem-Galliform Affinity for the Giant Extinct Flightless Bird Sylviornis neocaledoniae (Sylviornithidae, Galloanseres).

Worthy TH, Mitri M, Handley WD, Lee MS, Anderson A, Sand C - PLoS ONE (2016)

Bottom Line: Sylviornis neocaledoniae is found to be a stem galliform, distant from megapodiids, and the sister taxon to the extinct flightless Megavitiornis altirostris from Fiji, which we transfer to the family Sylviornithidae.These observations and its phylogenetic placement as stem galliforms makes it improbable that this species employed ectothermic incubation or was a mound-builder.Sylviornis neocaledoniae can therefore be excluded as the constructor of tumuli in New Caledonia.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia.

ABSTRACT
The giant flightless bird Sylviornis neocaledoniae (Aves: Sylviornithidae) existed on La Grande Terre and Ile des Pins, New Caledonia, until the late Holocene when it went extinct shortly after human arrival on these islands. The species was generally considered to be a megapode (Megapodiidae) until the family Sylviornithidae was erected for it in 2005 to reflect multiple cranial autapomorphies. However, despite thousands of bones having been reported for this unique and enigmatic taxon, the postcranial anatomy has remained largely unknown. We rectify this deficiency and describe the postcranial skeleton of S. neocaledoniae based on ~600 fossils and use data from this and its cranial anatomy to make a comprehensive assessment of its phylogenetic affinities. Sylviornis neocaledoniae is found to be a stem galliform, distant from megapodiids, and the sister taxon to the extinct flightless Megavitiornis altirostris from Fiji, which we transfer to the family Sylviornithidae. These two species form the sister group to extant crown-group galliforms. Several other fossil galloanseres also included in the phylogenetic analysis reveal novel hypotheses of their relationships as follows: Dromornis planei (Dromornithidae) is recovered as a stem galliform rather than a stem anseriform; Presbyornis pervetus (Presbyornithidae) is the sister group to Anseranatidae, not to Anatidae; Vegavis iaai is a crown anseriform but remains unresolved relative to Presbyornis pervetus, Anseranatidae and Anatidae. Sylviornis neocaledoniae was reconstructed herein to be 0.8 m tall in a resting stance and weigh 27-34 kg. The postcranial anatomy of S. neocaledoniae shows no indication of the specialised adaptation to digging seen in megapodiids, with for example, its ungual morphology differing little from that of chicken Gallus gallus. These observations and its phylogenetic placement as stem galliforms makes it improbable that this species employed ectothermic incubation or was a mound-builder. Sylviornis neocaledoniae can therefore be excluded as the constructor of tumuli in New Caledonia.

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The strict consensus tree from parsimony and ordered analysis with a molecular backbone constraint.In this analysis, relationships between taxa with molecular data (living taxa and moa) were constrained, with other (fossil) taxa free to move to their optimal positions within this backbone. Tree statistics: Length 1425, Consistency index = 0.2786, Homoplasy index = 0.7214, Retention index = 0.6295. The Bootstrap and probability values of the other analyses (Parsimony, unordered, Bayesian ordered and unordered) are shown, with a dash to indicate clade not found.
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pone.0150871.g013: The strict consensus tree from parsimony and ordered analysis with a molecular backbone constraint.In this analysis, relationships between taxa with molecular data (living taxa and moa) were constrained, with other (fossil) taxa free to move to their optimal positions within this backbone. Tree statistics: Length 1425, Consistency index = 0.2786, Homoplasy index = 0.7214, Retention index = 0.6295. The Bootstrap and probability values of the other analyses (Parsimony, unordered, Bayesian ordered and unordered) are shown, with a dash to indicate clade not found.

Mentions: Parsimony and Bayesian analyses of the morphological data with the molecular backbone constraint always placed S. neocaledoniae as a basal galliform. The parsimony analysis with ordered characters found 12 trees of length 1425; the strict consensus is shown in Fig 13, along with supports for retrieved nodes from all the "backboned" analyses. Sylviornis neocaledoniae along with M. altirostris fell outside of crown galliforms under all analyses, with varying support (Fig 13 Node A: bootstrap 70/72% and posterior probability 0.59/0.77, depending on whether characters were ordered/unordered). In six of the most parsimonious trees (MPTs) they were sister taxa, whereas in the other six MPTs, they formed successive branches on the stem. There is thus no evidence that either S. neocaledoniae or M. altirostris nest within crown Galliformes as close relatives of modern megapodes. Although outside the galliform crown, both taxa were robustly placed along the stem of Galliformes, by themselves in ordered parsimony analyses (Node B: bootstrap 82/70%) and together with Dromornis planei in Bayesian analysis (Node C, posterior probabilities 0.99/1.0). The relationships of the Holocene extinct megapode Mwalau walterlinii from Vanuatu were unresolved, as in six of the MPTs, it was the sister taxon to extant megapodiids, and in the remaining six MPTs, it was the sister taxon to extant galliforms. More complete specimens will be required to find resolution for this taxon. The fossil taxa Presbyornis pervetus and Vegavis iaai were recovered within crown Anseriformes with varying support (bootstrap 60/56%; pp 0.93/0.91); however, they were more strongly excluded from crown Anatidae (bootstrap 90/93%; pp 0.99/1.0). The lithornithids were retrieved with strong support as the sister group to extant tinamous, and thus deeply nested within palaeognaths (bootstrap 88/91%; pp 0.98/0.99).


Osteology Supports a Stem-Galliform Affinity for the Giant Extinct Flightless Bird Sylviornis neocaledoniae (Sylviornithidae, Galloanseres).

Worthy TH, Mitri M, Handley WD, Lee MS, Anderson A, Sand C - PLoS ONE (2016)

The strict consensus tree from parsimony and ordered analysis with a molecular backbone constraint.In this analysis, relationships between taxa with molecular data (living taxa and moa) were constrained, with other (fossil) taxa free to move to their optimal positions within this backbone. Tree statistics: Length 1425, Consistency index = 0.2786, Homoplasy index = 0.7214, Retention index = 0.6295. The Bootstrap and probability values of the other analyses (Parsimony, unordered, Bayesian ordered and unordered) are shown, with a dash to indicate clade not found.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814122&req=5

pone.0150871.g013: The strict consensus tree from parsimony and ordered analysis with a molecular backbone constraint.In this analysis, relationships between taxa with molecular data (living taxa and moa) were constrained, with other (fossil) taxa free to move to their optimal positions within this backbone. Tree statistics: Length 1425, Consistency index = 0.2786, Homoplasy index = 0.7214, Retention index = 0.6295. The Bootstrap and probability values of the other analyses (Parsimony, unordered, Bayesian ordered and unordered) are shown, with a dash to indicate clade not found.
Mentions: Parsimony and Bayesian analyses of the morphological data with the molecular backbone constraint always placed S. neocaledoniae as a basal galliform. The parsimony analysis with ordered characters found 12 trees of length 1425; the strict consensus is shown in Fig 13, along with supports for retrieved nodes from all the "backboned" analyses. Sylviornis neocaledoniae along with M. altirostris fell outside of crown galliforms under all analyses, with varying support (Fig 13 Node A: bootstrap 70/72% and posterior probability 0.59/0.77, depending on whether characters were ordered/unordered). In six of the most parsimonious trees (MPTs) they were sister taxa, whereas in the other six MPTs, they formed successive branches on the stem. There is thus no evidence that either S. neocaledoniae or M. altirostris nest within crown Galliformes as close relatives of modern megapodes. Although outside the galliform crown, both taxa were robustly placed along the stem of Galliformes, by themselves in ordered parsimony analyses (Node B: bootstrap 82/70%) and together with Dromornis planei in Bayesian analysis (Node C, posterior probabilities 0.99/1.0). The relationships of the Holocene extinct megapode Mwalau walterlinii from Vanuatu were unresolved, as in six of the MPTs, it was the sister taxon to extant megapodiids, and in the remaining six MPTs, it was the sister taxon to extant galliforms. More complete specimens will be required to find resolution for this taxon. The fossil taxa Presbyornis pervetus and Vegavis iaai were recovered within crown Anseriformes with varying support (bootstrap 60/56%; pp 0.93/0.91); however, they were more strongly excluded from crown Anatidae (bootstrap 90/93%; pp 0.99/1.0). The lithornithids were retrieved with strong support as the sister group to extant tinamous, and thus deeply nested within palaeognaths (bootstrap 88/91%; pp 0.98/0.99).

Bottom Line: Sylviornis neocaledoniae is found to be a stem galliform, distant from megapodiids, and the sister taxon to the extinct flightless Megavitiornis altirostris from Fiji, which we transfer to the family Sylviornithidae.These observations and its phylogenetic placement as stem galliforms makes it improbable that this species employed ectothermic incubation or was a mound-builder.Sylviornis neocaledoniae can therefore be excluded as the constructor of tumuli in New Caledonia.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia.

ABSTRACT
The giant flightless bird Sylviornis neocaledoniae (Aves: Sylviornithidae) existed on La Grande Terre and Ile des Pins, New Caledonia, until the late Holocene when it went extinct shortly after human arrival on these islands. The species was generally considered to be a megapode (Megapodiidae) until the family Sylviornithidae was erected for it in 2005 to reflect multiple cranial autapomorphies. However, despite thousands of bones having been reported for this unique and enigmatic taxon, the postcranial anatomy has remained largely unknown. We rectify this deficiency and describe the postcranial skeleton of S. neocaledoniae based on ~600 fossils and use data from this and its cranial anatomy to make a comprehensive assessment of its phylogenetic affinities. Sylviornis neocaledoniae is found to be a stem galliform, distant from megapodiids, and the sister taxon to the extinct flightless Megavitiornis altirostris from Fiji, which we transfer to the family Sylviornithidae. These two species form the sister group to extant crown-group galliforms. Several other fossil galloanseres also included in the phylogenetic analysis reveal novel hypotheses of their relationships as follows: Dromornis planei (Dromornithidae) is recovered as a stem galliform rather than a stem anseriform; Presbyornis pervetus (Presbyornithidae) is the sister group to Anseranatidae, not to Anatidae; Vegavis iaai is a crown anseriform but remains unresolved relative to Presbyornis pervetus, Anseranatidae and Anatidae. Sylviornis neocaledoniae was reconstructed herein to be 0.8 m tall in a resting stance and weigh 27-34 kg. The postcranial anatomy of S. neocaledoniae shows no indication of the specialised adaptation to digging seen in megapodiids, with for example, its ungual morphology differing little from that of chicken Gallus gallus. These observations and its phylogenetic placement as stem galliforms makes it improbable that this species employed ectothermic incubation or was a mound-builder. Sylviornis neocaledoniae can therefore be excluded as the constructor of tumuli in New Caledonia.

Show MeSH
Related in: MedlinePlus