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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 from parsimony and ordered analysis with only ingroup-outgroup constraints.The ingroup-outgroup constraint was (Palaeognaths ((neognaths) (galloanseres)) wherein all taxa were free to move within but not between these three clades. Three MPTs were found Length 1395, Consistency index = 0.2846, Homoplasy index = 0.7154, Retention index = 0.6404. The bootstrap and probability values of the other analyses (Parsimony, unordered, Bayesian ordered and unordered) are shown, with a dash to indicate that the clade not found. We consider this tree less plausible than the one in Fig 13 (see main text).
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pone.0150871.g014: The strict consensus from parsimony and ordered analysis with only ingroup-outgroup constraints.The ingroup-outgroup constraint was (Palaeognaths ((neognaths) (galloanseres)) wherein all taxa were free to move within but not between these three clades. Three MPTs were found Length 1395, Consistency index = 0.2846, Homoplasy index = 0.7154, Retention index = 0.6404. The bootstrap and probability values of the other analyses (Parsimony, unordered, Bayesian ordered and unordered) are shown, with a dash to indicate that the clade not found. We consider this tree less plausible than the one in Fig 13 (see main text).

Mentions: Parsimony and Bayesian analyses of the morphological data with only ingroup-outgroup constraints (palaeognaths ((neognaths) (galloanseres)) retrieved trees highly inconsistent with recent genetic data. In the parsimony analyses, Sylviornis neocaledoniae and Megavitiornis altirostris fall outside of crown Galliformes (Fig 14, Node A: bootstrap 77/84% ordered/unordered). However, in contrast to the molecular evidence (see Fig 13), tinamous emerge as basal palaeognaths, and megapodes are weakly resolved as a paraphyletic assemblage basal to all other living galliforms, which are monophyletic with strong bootstrap support (bootstrap 74/71% ordered/unordered). In the ordered analysis, S. neocaledoniae and M. altirostris are placed on the stem to Galliformes (Fig 14, Node B; bootstrap 65%) and Dromornis planei falls on the stem of Anseriformes with weak support (bootstrap 35%), while Vegavis iaai and Presbyornis pervetus fall within crown Anseriformes (bootstrap 72% and posterior probability 0.99, 1.0). The Bayesian analyses, in contrast, retrieved a monophyly of extant megapodes (consistent with molecular and morphological data) but then surprisingly placed a clade consisting of Sylviornis neocaledoniae, Megavitiornis altirostris and Dromornis as the sister group to megapodes (unordered) or within megapodes (ordered). These parsimony and Bayesian results are considered less plausible than corresponding analyses with the molecular backbone, and will not be discussed further.


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 from parsimony and ordered analysis with only ingroup-outgroup constraints.The ingroup-outgroup constraint was (Palaeognaths ((neognaths) (galloanseres)) wherein all taxa were free to move within but not between these three clades. Three MPTs were found Length 1395, Consistency index = 0.2846, Homoplasy index = 0.7154, Retention index = 0.6404. The bootstrap and probability values of the other analyses (Parsimony, unordered, Bayesian ordered and unordered) are shown, with a dash to indicate that the clade not found. We consider this tree less plausible than the one in Fig 13 (see main text).
© Copyright Policy
Related In: Results  -  Collection

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

pone.0150871.g014: The strict consensus from parsimony and ordered analysis with only ingroup-outgroup constraints.The ingroup-outgroup constraint was (Palaeognaths ((neognaths) (galloanseres)) wherein all taxa were free to move within but not between these three clades. Three MPTs were found Length 1395, Consistency index = 0.2846, Homoplasy index = 0.7154, Retention index = 0.6404. The bootstrap and probability values of the other analyses (Parsimony, unordered, Bayesian ordered and unordered) are shown, with a dash to indicate that the clade not found. We consider this tree less plausible than the one in Fig 13 (see main text).
Mentions: Parsimony and Bayesian analyses of the morphological data with only ingroup-outgroup constraints (palaeognaths ((neognaths) (galloanseres)) retrieved trees highly inconsistent with recent genetic data. In the parsimony analyses, Sylviornis neocaledoniae and Megavitiornis altirostris fall outside of crown Galliformes (Fig 14, Node A: bootstrap 77/84% ordered/unordered). However, in contrast to the molecular evidence (see Fig 13), tinamous emerge as basal palaeognaths, and megapodes are weakly resolved as a paraphyletic assemblage basal to all other living galliforms, which are monophyletic with strong bootstrap support (bootstrap 74/71% ordered/unordered). In the ordered analysis, S. neocaledoniae and M. altirostris are placed on the stem to Galliformes (Fig 14, Node B; bootstrap 65%) and Dromornis planei falls on the stem of Anseriformes with weak support (bootstrap 35%), while Vegavis iaai and Presbyornis pervetus fall within crown Anseriformes (bootstrap 72% and posterior probability 0.99, 1.0). The Bayesian analyses, in contrast, retrieved a monophyly of extant megapodes (consistent with molecular and morphological data) but then surprisingly placed a clade consisting of Sylviornis neocaledoniae, Megavitiornis altirostris and Dromornis as the sister group to megapodes (unordered) or within megapodes (ordered). These parsimony and Bayesian results are considered less plausible than corresponding analyses with the molecular backbone, and will not be discussed further.

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