Galloanserae: Anseres

Taxa on this Page

1. Anatalavis X
2. Anseranas 
3. Anseres

Anseres

He ran till he came to a great big pen.
The ducks and the geese were kept therein.

-- Folk Song

Anseres is, indeed, a "great big pen" in phylospace. It includes ducks, geese, presbyornithids and some related forms. It extends from at least the Maastrichtian to the present day. Anatomically, the Anseres have specialized beaks -- the flattened "duck bill" and some related cranial adaptations. The body plan is otherwise conservative. Many of the Anseres are relatively large-bodied. Virtually all live in relatively close relationship to wetlands or open water and so have varying degrees of aquatic adaptation. However, these aquatic adaptations are convergent on the specializations of other shorebirds, which has created considerable confusion over the years. Perhaps it confuses the birds as well, since (sterile) hybrids between duck species are common. In overall form, the Anseres can be viewed as a line of geese -- big-bodied, long-necked, relatively terrestrial, unspecialized herbivores -- which has also produced two highly successful clades of more aquatic and gracile offshoots, the presbyornithids and ducks.

The Anseres probably derived from more terrestrial stock in the Late Cretaceous. This is not quite as clear as it might be. The leading phylogenies of this region are generally based on Livezey's work [L97] which assumes the Tinamiformes as the primary outgroup. Thus, terrestriality is assumed to be the primitive condition, something that remains to be proven. The first fossil remains of Anseres are early Maastrichtian presbyornithids [H02] [K+02] and late Maastrichtian (possibly earliest Paleocene) remains of Anatalavis[OP87]. Unfortunately, these are all post-cranial fossils, so the status of the key cranial adaptations in the Cretaceous remains unknown. Nonetheless, from the plentiful remains of Eocene presbyornithids and the living magpie goose, Anseranas (a close relative of Anatalavis), we can be confident that even these early Anseres possessed many of the characteristic skull features of modern geese.

These characters include the bill itself, a relatively large flattened rhamphotheca with the upper bill overlapping the lower, supported by an enlarged premaxilla which is rounded anteriorly. The bill is supported medially by a raised beam formed by the maxillae. This beam runs down the center of the bill and, in more derived birds has been adapted to accommodate a powerful tongue used in filter feeding.  Geese, of course, do not rely on this tongue for getting food into the mouth, so the hyoid apparatus tends to be simple, but powerful. In order to make room for the bill, the jugal bar reaches the quadrate from a position more laterally than is usually the case. This state of affairs requires, in turn, changes in the quadrate. The more lateral position of the jugal bar articulation provides more room medially for muscle attachment, which is convenient, since more muscle mass is needed to manipulate the enlarged beak.

The Anseres seem to have committed rather early to specialized structures of the upper beak, some of which have been mentioned. In addition, Anseres have a well-developed ball-in-socket articulation between the pterygoid and palatine and other features specific to particular family groups. The lower beak is relatively simple, although Anseres do have a specialized "flex zone" in the lower jaw, rather than a broadly flexible mandible.

With respect to phylogeny, the most basal Anseres are usually believed to be simiklar to Anseranas and Anatalavis. Traditionally, these were united as the "Anseranatidae."  However, it seems that these two forms actually do not form a clade, but are merely successive goose-like branches from a basic goose-like stem [D00] [D01]. The characters which they share are essentially all primitive for Anseres. The first real divergence from this plan is Presbyornithidae. The point of divergence, i.e. the clade Presbyornis + Anser, is the subject of the next page. ATW030818.

References: Dyke (2000) [D00]; Dyke (2001) [D01]; Hope (2002) [H02]; Livezey 1997) [L97]; Kurochkin et al. 2002) [K+02]; Olson & Parris (1987) [OP87].

Descriptions

Anseres: ducks, geese, swans.

Notes: [1] The notation "[L97*]" indicates a synapomorphy based on the osteological dataset of [L97] run under PHYLIP with all characters unordered. The usual "$" means a synapomorphy identified by Livezey [L97].

Links: BIRDS OF INDIANA: Order Anseres. Lamellirostral Swimmers; [The] genera of birds - comprising their generic characters, a ...; Pluimvee etc. Dutch).

Anseranas: A. semipalmata Latham 1798.

Range: Recent of Australia & New Guinea [WS00]. [3]

Phylogeny: Anseres: (Anatalavis + Anatoidea) + *.

Characters: to 92 cm; beak short and stout, slightly hooked at the end [O99]; beak red with a grey tip; frontals with laterally compressed swelling [L97*]; frontal area with large bony casque [O99]; attachment for mandibular depressor not greatly developed [O99]; premaxilla with posterior process under jugal [W+97]; palatines laterally concave [W+97]; pterygoid, basipterygoid articulation elongate oval [O99]; pterygoid with quadrate articulation relatively small [O99]; thoracic vertebrae without lateral pneumatic foramina [O99]; costal ribs with dorsal pneumatic foramina vestigial [L97*]; sternum with manubrial spine absent (reversal) [L97*]; sternum with pneumatic pores on internal face near midline [L97*]; sternum with pneumatic foramina on internal face absent (reversal) [L97*]; furcula with thick, pneumatized symphysis [O99]; coracoid with procoracoid process broad & blunt [O99]humerus not unusually stout [O99]; sequential molt of primary remiges (no flightless season) [H+96] [L97]; pelvis with anterior ilium narrow [O99]; legs long & stout, colored orange-yellow; tarsometatarsus with medial trochlea for pes II transversely thickened [L97*]; digits half-webbed [H+96] [L97]; digits heavily clawed [H+96]; pes IV opposable [H+96]; coloring black & white, with naked red face; no sexual dimorphism; colonial; mating group is often 1 male & 2 females [H+96]; triads stable from year to year [H+96]; both females in triad reduce reproductive output [H+96]; nesting synchronized, with timing dependent on wet season onset [WS00]; seasonal migration between feeding & nesting areas [WS00]; amount of nesting decreases with delayed monsoon [WS00][2]; nest deep bowl on a floating island made from water plants; chicks remain with parents for full year [H+96]; vocalizes loud honk; herbivorous; found in freshwater lakes, slow-moving waterways and swamps; migrates between interior swamps and coastal lakes; long lived (to 30 yrs in the wild) [WS00].

Notes: [1] When run on PHYLIP, the dataset from [L97] yields a single tree, with Anseranas and Anatalavis as sequential branches, not a distinct clade. Dyke [D00] comes to the same conclusion with a different data set. Olson [O99] also notes that the two members of this family have little in common except for the unusual furcula and distal pneumatic fossa of the coracoid. If so, "Anseranatidae" is the paraphyletic parent of Anatidae. The notation "[L97*]" indicates an apomorphy based on the osteological dataset of [L97] run under PHYLIP with all characters unordered. [2] [WS00] believe that the trigger is metabolic health. Early rains trigger the growth of high-protein grasses, and the animals have time to improve their physical condition (usually poor after migration) before high water, when conditions are ideal for nesting.  [3] range appears to be moving north, out of S. Australia and into North Australia, New Guinea and Indonesia.

Image: from Pacific Island Books, by permission.

Links: Magpie goose, Anseranas semipalmata; Ganso Overo (Spanish).

References: Horn et al. 1996) [H+96]; Livezey (1997) [L97]; Olson (1999) [O99]; Whitehead & Saalfeld (2000) [WS00]; Worthy et al. (1997) [W+97]. ATW030818.

Anatalavis: Olson & Parris 1987.  A. rex (Telmatornis rex Shufeldt 1915) Olson & Parris 1987,  A. oxfordi Olson 1999

Range: Late Cretaceous (Maastrichtian) to Early Eocene Ypresian) of Europe (England) & North America (New Jersey and probably elsewhere in the Eastern US).

Phylogeny: Anseres:: Anseranas + *.

Characters: very broad, shallow, duck-like bill, not hooked [O99]; casque absent [O99]; nares short, broad & round [O99]; internarial bar very narrow [O99]; interorbital bar broad (compared to Anseranas) [O99]; strong nuchal crests [O99]; postorbital process short & blunt [O99]; anterior temporal fossa with indistinct mandibular adductor scars [O99]; enlarged attachment for depressor mandibulae in posterior portion of temporal fossa [O99]; occipital fontanelles present as two narrow, vertical slits [O99]; occipital condyle large [O99]; secondary palate may have been absent or not ossified [O99]; pterygoid with large, round facets for basipterygoid articulation [O99]; pterygoid quadrate articulation large [O99]; pterygoid palatine articulation offset from long axis [O99]; articular with large, bladelike retroarticular process, curving dorsally [O99]; retroarticular process unusually short, deep & (transversely?) thick [O99]; thoracic vertebrae with small lateral pneumatic foramina [O99]; sternum with carina apex rounded & undercut by a broad notch (??) [O99]; sternum with manubrial spine (absent in Anseranas) [O99]; furcula (see image) with very thin, non-pneumatic symphysis [O99]; scapula broader than Anseranas, with acromion longer & more pointed [O99]; coracoid with narrow, pointed procoracoid process [O99]; coracoid, procoracoid process with distinct circular procoracoid foramen [O99]; humerus very short & robust [OP87] [O99]; humeral head & internal tuberosity massive [O99]; humerus, capital groove very wide & deep [O99]; tricipital fossa small [O99]; humeral shaft strongly curved [OP87] [O99]; olecranon fossa narrow & very deep [OP87]; humerus with brachial depression relatively small, narrow & shallow [OP87]; distal humerus strongly expanded [OP87]; carpometacarpus, articular process for major digit has a prominent, anteriorly directed flange? spur? [L97*]; pelvis anterior short, strongly expanded & rounded, resembling that of ibises & wading birds [O99]; anterior ilium very broad & "deeply excavated for the iliotrochantericus muscles, leaving a broad, well-defined dorsal ridge" [O99]; ilium fused to synsacrum [O99]; likely filter feeder [O99].

Note: [1] A. rex is from the Hornerstown Formation and may be Early Paleocene, rather than Maastrichtian. A. oxfordi from the London Clay is much larger and constructed more along the lines of Anseranas. [2] When run on PHYLIP, the dataset from [L97] yields a single tree, with Anseranas and Anatalavis as sequential branches, not a distinct clade. Dyke [D00] [D01] comes to the same conclusion with a similar data set. Olson [O99] also notes that Anatalavis and Anseranas have little in common except for the unusual furcula and distal pneumatic fossa of the coracoid.  " Anseranatidae" is therefore not monophyletic. The notation "[L97*]" indicates an apomorphy based on the osteological dataset of [L97] run under PHYLIP with all characters unordered.  [3] Olson [O99] notes that combination of weak adductors, strong depressors & strong nuchal crest (neck muscles) suggests filter feeding. However, he also states that the humerus is more like that of a raptor, and clearly anomalous. [4] Olson [O99] does not remark on it, but the distal humerus is strikingly like Presbyornis, including the "crossed condyles."

Image: (left) furcula of Anatalavis oxfordi from [O99].

Links: Ducks present and past (was Re- ARE ORNITHOPODS BORING-); Mesozoic Neornithes; Aves Translation and Pronunciation Guide Best on the Web); PalAss Annual Conference Abstracts 2000;  

References: Dyke (2000) [D00]; Dyke (2001) [D01]; Livezey 1997) [L97]; Olson (1999) [O99]; Olson & Parris (1987) [OP87]. ATW030818.