A field guide to mesozoic birds and other winged dinosaurs

Barrett’s Seabird Enaliornis barretti
Time: 100 Ma ago Location: England, UK Habitat: Cambridge Greensand Formation.
Shores and lagoons surrounding semi-tropical islands in a shallow sea. Size: WS unknown;
BL ~55cm (1.8ft); TL unknown Features: Marine hesperornitheans known from a partial
skeleton & a number of fragments. Head small, but most of the skull & snout unknown.
Legs very long, w/ long, robust tibia, short & stocky femur (probably less than half tibia
length), & short but robust tarsus shorter than the femur. Distinguished by their small
size, primitive characteristics, & internal characteristics of the hind limbs & pelvis (lack
of femoral neck, mid-sized antitrochantor, keel beneath the synsacrum). Biology: These
small seabirds combined some features in common with more advanced hesperornitheans,
while retaining some primitive features found in ichthyornitheans & other carinatans.
They were therefore probably coastal divers or dippers which may have retained some
flight ability, though the wing is not known.
Tanke’s Pasquia Bird Pasquiaornis tankei
Time: 95 Ma ago Location: Saskatchewan, Canada Habitat: Ashville Formation, nearshore
marine enviornment in the northern Western Interior Seaway Size: WS >36cm
(1.2ft); BL ~70cm (2.3ft); TL unknown Features: Jaws long & toothed. Wings relatively
long. Legs long & slender. Biology: The legs were positioned more directly under the body
than in later hesperornitheans, possibly allowing a waddling gait on land. The toes could
not twist during proportion as in lobed-toe birds, indicating normally webbed feet. The
relatively long & robust wing bones suggest possible retention of flight ability, though the
sternum is unknown. Probably surface swimmers (Sanchez 2012).
Varner’s Brodkorb Bird Brodavis varneri
Time: 78 Ma ago Location: Kansas, USA Habitat: Sharon Springs Member, Pierre Shale
Formation. Relatively shallow river deltas and estuaries opening into the Western Interior
Seaway. Size: WS unknown; BL ~90cm (3ft); TL unknown Features: Marine hesperornitheans.
Body long & barrel-shaped, w/ short torso & long hips. Legs very long, w/ tibia
over half the length of the torso + hips. Tarsus short & stocky, less than ¼ tibia length. Neck
long, probably equal in length to torso + hips. Wings unknown. Biology: The hip bones
of these birds were not as advanced & highly fused as in related species. This, compared
w/ the robust foot bones, may suggest a slightly different method of underwater propulsion
compared w/ similar species inhabiting deeper saltwater environments off the coasts.
The skeleton was overall more lightly built & not as solid as other hesperornitheans. This
implies a more limited diving ability, restricting these birds to near-surface feeding. The
lighter skeleton may also suggest some flight ability was retained.
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