Galloanserae: Anseres: Cnemiornis

Taxa on this Page

1. Cnemiornis X

Cnemiornis

Cnemiornis is an extinct flightless "goose" from New Zealand. Two species are known, each of which was endemic to one of the two main islands of New Zealand. The bird was never particularly common. It seems to have done best in Late Pleistocene times, as the glaciers of the last ice age were retreating. It became extinct shortly after the arrival of the Polynesians in New Zealand, presumably as a result of human predation.

There's considerable doubt about the proper place of Cnemiornis in the order of things. Livezey [L96] (whom we follow), places it just North of the Anatidae (Anas + Anser?). However, Worthy et al. [W+97] had the advantage of a new specimen, by far the most complete ever found; and they conclude that Cnemiornis falls within the modern geese, as the sister of the living, but comparatively primitive, Cape Barren goose, Cereopsis. There argument is sound, but we prefer Livezey's study for three reasons.

First, most of the characters use to show similarity between Cereopsis and Cnemiornis were known before the new specimen. If the characters were phylogenetically informative over a reasonable range, this similarity ought to have shown up in the previous study.Second, most of the points scored against Livezey's use of character data could equally well be taken to place Cereopsis outside Anatidae, rather than placing Cnemiornis within it. Finally, consistent with this last point, [W+97] do not actually find that Cnemiornis is an anatid. Rather they find a trichotomy of ducks, geese, and a Cereopsis-Cnemiornis clade. Thus, Worthy's data is also consistent with Cnemiornis being basal to the Anatidae, although it does not require this result.

References: Livezey (1996) [L96]; Worthy et al. (1997) [W+97]. ATW030322.

Descriptions

Cnemiornis: C. calcitrans Owen, 1866; C. gracilis Forbes, 1894.  Extinct flightless geese of New Zealand.

Range: Late Pleistocene to Early Holocene of New Zealand.

Phylogeny: Anatoidea:: Anatidae + *.

Characters: premaxilla not fused & free to flex dorsoventrally [W+97]; premaxilla lacks posterior process under jugal [W+97]; rostrum above nares is slightly convex [L96]; lacrimal extends over part of premaxilla - cranial junction [W+97]; lacrimal forms weak supraorbital process [W+97]; large supraorbital salt gland bounded medially by sharp ridge [W+97]; several foramina connecting salt gland area & orbit [W+97]; orbit rimmed by 2mm ridge of bone [W+97]; jugal arch straight & slender, linking premaxilla & quadrate [W+97]; jugal overlapped by palatines anteriorly [W+97]; quadrate, orbital process long, terminating above midpoint of basipterygoid process [W+97]; quadrate, orbital process with lateral protuberance at midpoint [W+97]; quadrate, medial & posterior condyle in one articular structure with mandible [W+97]; quadrate, quadratojugal cotyle located on dorsal expansion of mandibular process [W+97]; within tympanic cavity with vertical bar parallel to paroccipital process, linking squamosal with parasphenoid wing [W+97]; occipital fontanelles present in C. gracilis, absent in C. calcitrans [W+97]; palatines laterally convex [W+97]; palatines fused medially, with long anterior process, possibly vomer, bisecting choana [W+97] [3]; pterygoid, basipterygoid articular processes robust & oval [W+97]; all vertebrae except axis & atlas with two crests, which develop into transverse ridges to #14 [W+97]; 17 cervicals [L96]; transverse ridges converge dorsally (14-16) to form a neural spine [W+97]; vertebrae 17-21 with ventral spines [W+97]; total 23 dorsals plus 2 articulating freely with pelvis [W+97]; 6 pairs of presacral dorsal ribs (18-23), of which 5 19-23) articulate with sternal ribs [W+97]; sternum without medial incisure [L96]; sternum with carina greatly reduced [L96]; furcula U-shaped, without hypocleideum or coracoid facet [L96] [W+97]; furcula with complex pneumatic foramina below acromial facet [L96] [W+97]; scapula with strongly reduced acromion process [W+97]; coracoid without sulcus separating humeral facet and acrocoracoid process [W+97]; coracoid, procoracoid process with large procoracoid foramen not enclosed medially [W+97] [O99]; coracoid, sternal end concave in both dorsal & ventral views [W+97]; coracoid, sternal articulation poorly developed [W+97]; humerus with ridge of humeral head not including external tubercle [W+97]; capital groove short & not undercutting head "much" [W+97];  humerus with external tubercle raised on a platform above the surrounding bone [W+97]; humerus with deltopectoral crest evenly rounded, grading smoothly into shaft & concave [W+97] [4]; radius shaft triangular in cross section [W+97]; radial shaft somewhat expanded distally [W+97]; carpometacarpus with alular process very small [W+97]; carpometacarpus with extensor process short and not spur-like [W+97]; carpometacarpus with phalangeal facets for major & minor digits extending equally [W+97]; carpometacarpus with long distal metacarpal fusion [W+97] [5]; major digit with third phalanx present [W+97]; ribs not fused to sacrum [W+97]; ilium perforated by foramina of variable size above antitrochanters [W+97]; ischia with large foramina near base [W+97]; pubes not fused to posterior margin of the ischium [W+97]; pubes, posterior end angled somewhat ventrally & terminating in slightly expanded knobs [W+97]; femur, head angled about 110-120° from shaft [W+97*]; femur with anterior edge of external condyle elevated from shaft [W+97]; "fibular condyle extending farther distally than its point of junction with the external condyle" (beats me!) [W+97]; tibiotarsus with trochleae for digits II & IV extending distally to near equal extent [W+97]; pes phalangeal formula ?3450; ungual II straight, ungual IV curved & ungual III intermediate [W+97].

Notes: [1] may have been close to extinction before arrival of humans. [2] Worthy et al. [W+97] believe that Cnemiornis is a "true" goose, closely related to Cereopsis, the flighted Cape Barren Goose of Australia. [3] I have labeled the palate with a different interpretation, assigning the median, fused portion to the maxillae. In all probability, particularly given the appearance of the skull in lateral view, Worthy et al. are correct. In either case, the small, median bone is likely the vomer, as [W+97] state. [4] "concave anconally" [W+97]. Can this be correct?  Concave ventrally, in any case. [5] From the figure, this is true of the right limb, but perhaps not the left.  [W+97] also note a "prominent tuberosity at the anterior end of metacarpal III."  Anterior end?  [6] the notation [W+97*] indicates anatid synapomorphies found by Livezey, as discussed by Worthy et al. The latter authors generally disagree.

Links: Worthy--Late-Glacial avifaunas of Te Aute, Wheturau; WorthySwabey Avifaunal .P65; Systematic Biology 45(4) Abstracts.

References: Livezey (1996) [L96]; Olson (1999) [O99]; Worthy et al. (1997) [W+97]. ATW030320.