This video says about itself:
3 May 2009
Hesperornis is an extinct genus of flightless aquatic birds that lived during the Santonian to Campanian sub-epochs of the Late Cretaceous (89-65 mya). One of the lesser known discoveries of paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an important early find in the history of avian paleontology. Famous locations for Hesperornis are the Late Cretaceous marine limestones from Kansas and the marine shales from Canada, but the genus had probably a Holarctic distribution.
Hesperornis was a large bird, reaching up to 2 meters (6.5 feet) in length. It had virtually no wings, and swam with its powerful hind legs. The toes were probably lobed rather than being webbed, as in today’s grebes; like in these, the toes could rotate well, which is necessary to decrease drag in lobed feet but not in webbed ones such as in loons, where the toes are simply folded together.
Like many other Mesozoic birds such as Ichthyornis, Hesperornis had teeth in its beak which were used to hold prey (most likely fish). In the hesperornithiform lineage they were of a different arrangement than in any other known bird (or in non-avian theropod dinosaurs), with the teeth sitting in a longitudinal groove rather than in individual sockets, in a notable case of convergent evolution with mosasaurs.
The first Hesperornis specimen was discovered in 1871 by Othniel Charles Marsh. Marsh was undertaking a second western expedition, accompanied by ten students. The team headed to Kansas where Marsh had dug before. Aside from finding more bones belonging to the flying reptile Pteranodon, Marsh discovered the skeleton of a “large fossil bird, at least five feet in height”. The specimen was large, wingless, and had strong legs—Marsh considered it a diving species. Unfortunately, the specimen lacked a head. Marsh named the find Hesperornis regalis, or “great ruling bird” [Western ruling bird].
Hesperornis hunted in the waters of such contemporary shelf seas as the North American Inland Sea, the Turgai Strait and the prehistoric North Sea, which then were subtropical to tropical waters, much warmer than today. They probably fed mainly on fish, maybe also crustaceans, cephalopods and mollusks as do the diving seabirds of today. Their teeth were helpful in dealing with slippery or hard-shelled prey.
On land, Hesperornis may or may not have been able to walk. They certainly were not able to stand upright like penguins as in the early reconstructions. Their legs attached far at the back and sideways, with even the lower leg being tightly attached to the body. Thus, they were limited to a clumsy hobble at best on land and would indeed have been more nimble if they moved by sliding on their belly or galumphing. Indeed, the leg skeleton of the hesperornithids was so much adapted to diving that their mode of locomotion while ashore, as well as where it laid its eggs and how it cared for its young is a matter of much speculation.
Some have even pointed out that it cannot be completely ruled out that these birds were ovoviviparous instead of incubating their eggs. In any case, young Hesperornis grew fairly quickly and continuously to adulthood, as is the case in modern birds, but not Enantiornithes. More young birds are known from the fossil record of the more northernly sites than from locations further south. This suggests that at least some species were migratory like today’s penguins which swim polewards in the summer.
Hesperornis were preyed upon by large marine carnivores. Tylosaurus proriger specimen SDSMT 10439 contains the bones of a Hesperornis in its gut, for example.
Now, a relative of Hesperornis has been discovered.
From the Perot Museum of Nature and Science in the USA:
Amateur collectors in Japan discover country’s first and oldest fossil diving bird
August 8, 2017
Summary: Two brothers from a small town in Hokkaido, Japan, made the discovery of their lives — the first and oldest fossil bird ever identified in their country. Identified as a new species, it has been named Chupkaornis keraorum.
During a walk near a reservoir in a small Japanese town, amateur collectors made the discovery of their lives — the first and oldest fossil bird ever identified in their country.
After sharing their mysterious find with paleontologists at Hokkaido University, brothers Masatoshi and Yasuji Kera later learned the skeletal remains were that of an iconic marine diving bird from the Late Cretaceous Period, one that is often found in the Northern Hemisphere but rarely in Asia. The remarkable specimen — which includes nine skeletal elements from one individual, including the thoracic vertebrae and the femoral bones — is being heralded as the “best preserved hesperornithiform material from Asia” and to be “the first report of the hesperorinthiforms from the eastern margin of the Eurasian Continent.”
Identified as a new species, it has been named Chupkaornis keraorum — Chupka is the Ainu word used by indigenous people from Hokkaido for ‘eastern,’ and keraorum is named after Masatoshi and Yasuji Kera, who discovered the specimen. The bird would have lived during the time when dinosaurs roamed the land.
The scientific paper describing the find, entitled “The oldest Asian Hesperornithiform from the Upper Cretaceous of Japan, and the phylogenetic reassessment of Hesperornithiformes,” has been posted on the Journal of Systematic Palaeontology website.
“This amazing find illustrates the special relationship paleontologists and other scientists have with ordinary citizens who come upon interesting and unusual objects,” said Tanaka. “Thanks to the wisdom and willingness of Masatoshi and Yasuji Kera to share their discovery with us at Hokkaido University, they have made a major contribution to science, and we are very grateful.”
The bones, estimated to be anywhere from 90 million to 84 million years old, were unearthed from the Upper Cretaceous Kashima Formation of the Yezo Group in Mikasa City, Hokkaido. The fossil bird consists of four cervical vertebrae, two thoracic vertebrae, the distal end of the left and right femora, and the middle part of the right fibula. The specimen is currently housed in the collection of the Mikasa City Museum in Hokkaido, Japan.
“Hespeornithiforms is the oldest group of birds that succeeded to adapt for diving in ocean. This study provides better understanding in the early evolution of this group and the origin of diving in birds,” added Tanaka.
Chupkaornis has a unique combination of characteristics: finger-like projected tibiofibular crest of femur; deep, emarginated lateral excavation with the sharply defined edge of the ventral margin of that the thoracic vertebrae (those vertebrae in the upper back); and the heterocoelous articular surface of the thoracic vertebrae. Phylogenetic analysis of this study revealed that Chupkaornis is one of the basal hesperornithiforms, thereby providing details of the evolution of this iconic group of diving birds.
“In Japan, many important vertebrate fossils have been discovered by amateurs because most of the land is covered with vegetation, and there are few exposures of fossil-bearing Cretaceous rocks. This research is a result of collaboration with amateurs, and I am thankful to their help and understanding of science,” said Kobayashi.
Hesperornithiformes were toothed, foot-propelled diving birds and one of the most widely distributed groups of birds in the Cretaceous of the northern hemisphere. These birds had extremely reduced forelimbs and powerful hind limbs, suggesting that they were flightless sea-going predatory birds. Most of hesperornithiform fossils have been discovered from North America so far. The discovery of Chupkaornis, the oldest Asian hesperornithiform, suggests that basal hesperornithiform had dispersed to the eastern margin of Asia no later than 90 million to 84 million years old.
The discovery has broader aspects — and that’s why Dr. Fiorillo, curator and vice president of research and collections at the Perot Museum of Nature and Science, is involved. Dr. Fiorillo is considered one of the world’s preeminent experts on arctic dinosaurs for his decades of research in Alaska. He has deep interest in the Beringia land bridge that connects North America to Asia. He was asked to collaborate on this discovery because several of the co-authors of the paper, including Kobayashi and lead-author Tanaka, have been members of his field team during past Alaska expeditions.
“This study not only tells important new information about the evolution of this unusual group of birds, it also helps further our understanding of life in the ancient northern Pacific region, more specifically what was going on in the ocean while dinosaurs walked the land” said Fiorillo.