The skull is either vaulted or flattened, with a sharp and narrow beak. The
paroccipital processes are shorter and more rounded, and the basi-occipital
tubercles more prominent than in _Anomalopteryx_, while the quadrate and
mandible resemble the same bones in that genus somewhat closely. The
sternum is flat and very broad and short, with no coracoidal facets, a very
small xiphisternal notch, broad and short costal processes, and widely
divergent lateral processes; while there are only two costal articulations.
The pelvis is extremely low and wide, with the anterior wall of the
acetabulum very deeply concave, the ventral surface of all the vertebrae
behind the true sacrals narrow and convex, and from which the very broad
sacral ribs ascend to join the ilium, of which the inferior postacetabular
border is very sharp, and descends far below the level of the ribs. There
is no pectineal process to the pubis. The tibio-tarsus is very short, with
the shaft curved outwards, the distal extremity markedly inflected, and the
fibular ridge much shorter than in the other genera. The fibular border
below the smooth space at the distal extremity of the fibular ridge is
extremely rough; and the distal extensor tubercle is very prominent, being
situated partly on the line of the upper half of the extensor groove,
instead of being altogether external to the same.
The tarso-metatarsus is still shorter and wider than in _Emeus_, the width
at the middle of the shaft being usually rather more than one third of the
length. The third trochlea is more prominent than in the other genera, and
rises very abruptly from the shaft, the outer border of the anterior
surface usually expanding suddenly at the proximal extremity, and the outer
ridge of this surface being always more prominent than the inner, whereas
in the other genera the opposite condition obtains. The femur, as compared
with that of _Dinornis_, is very much shorter and thicker, with a longer
neck, and the head rising and projecting very considerably, the linea
aspera mainly forming a rough nodule near the distal end of the shaft, the
outer surface of the distal extremity more suddenly expanded, and the
popliteal depression larger, more open, and leading to the inner surface of
the shaft by a more distinct channel. The profile of the inner condyle is
wider antero-posteriorly, and more rounded, the anterior intertrochlear
surface being deeply channelled.
The phalangeals of the pes are much shorter and stouter than in _Dinornis_,
the proximal surface of the terminal segments generally presenting a
trefoil-shaped contour. The length of the tarso-metatarsus is very much
{214} less than half that of the tibio-tarsus. In the vertebral column the
cervicals are short with very stout centra, the prezygopophyses in the
middle region being nearly horizontal and separated from one another by a
wide channel. The posterior face of the centra is tall and narrow, and the
neural spines of the last two vertebrae much inclined forward. In the
dorsals there is usually no anterior pneumatic foramen till the fourth (or
the last with a distinct haemal carina), this foramen being situated on the
line of the anterior border of the rib-facet. The third and fourth dorsals
are extremely compressed. Throughout the series also the neural spines and
transverse processes are comparatively long. Additional characters of the
skull are that the sphenoidal rostrum is expanded in a lance-like shape at
the anterior extremity, in a manner unlike that of any of the other genera.
Then the supraoccipital never has a very strongly developed median
prominence, and the temporal fossae are comparatively short. The mandible
may be readily distinguished from that of the other genera by the low
position of the inner aperture of the dental canal, which pierces the bone
obliquely to join the small lateral vacuity.
Type of the genus: _Pachyornis elephantopus_ (Owen).
Number of species: 8.