New avian fossil

In Howard's New Avian Fossil research she found an extinct family of seabirds.^[7] Howard was allowed to research a coracoid bone (between the shoulder blade and sternum) discovered for a species of bird not yet known by the public record. She concluded through previous evidence and modern avians that the bird was a previously unknown species of water bird by the shape of the shoulder and chest bone.^[8] She named this family of pelecaniformes seabirds plotopteridae.^[7]

Review of extinct avian genus

Howard conducted an experiment in which she took wasps from their home ecosystem and brought them to a greenhouse to see how they would take to the conditions of isolation and whether or not they would nest in that environment.^[9] After corrections to the methodology of the experiment, she was able to collect 41 nests to study the structure of their nesting.^[9]

The avifauna of Emeryville Shellmound

Howard's 1929 dissertation, "The Avifauna of Emeryville Shellmound" was particularly influential at the time. The dissertation she wrote thoroughly labelled ornithological fossil specimens, and paired the terms with visual representations.^[4] This allowed common terminology to be taught and widely popularized her work in the field.^[4] Her diagrams were eventually phased out after Nomina Anatomica Avium was published in 1997.^[4] The Avifauna of Emeryville Shellmound was important because it set the grounds of vocabulary for avian paleontology.^[10] Howard detailed, named and labelled a baseline for the skeletal makeup of all birds.^[10] This work solidified her significance in the world of paleontology and continues to stay a point of agreement for paleontologists of all levels.^[10] The names used are still widely referenced and give a strong baseline when labelling unknown species.^[10]

A census of the Pleistocene birds

Howard compared two studies regarding the Pleistocene animals of the Rancho La Brea region.^[11] One of them was a census conducted by Dr. Chester Stock regarding mammals of the region, while the other was a census of the birds.^[11] This entry sought the common factors, if any, between the two groups. She found that there was a limitation on the age of the animals from the Rancho La Brea exhibit. This effect was only manifested in the specimens that came from the early to the middle part of the late Pleistocene era.^[11]

• Howard, Hildegarde (1929), "The avifauna of Emeryville shellmound", University of California Publications in Zoology, 32 (2): 301–394
• Howard described the first "toothed" bird from North America and assigned the name "Osteodontornis" to it.^[12]
• Howard, Hildegarde (1962), "Fossil Birds", Science Series, 17: 44
• Howard, Hildegarde (1969), "A New Avian Fossil from Kern County, California", The Condor, 71 (1): 68–69, doi:10.2307/1366050, JSTOR 1366050
• Howard, Hildegarde (1970), "A review of the extinct avian genus, Mancalla", Contributions in Science, 203: 1–12, doi:10.5962/p.241190, S2CID 89964688

Examination of abnormal wing of a pintail duck

In this paper, Howard examined the possibility of regeneration after a man claimed that a Northern pintail duck who had its wing shot off was able to grow it back. When the specimen was submitted to the Los Angeles Museum,^[13] it was noted that there was a new portion joined to the old portion. The entry detailed this evidence; however, Howard did not conclude that this was the regeneration of the bones, since it had never been recorded before. She kept the possibility open because of the close relation between reptiles and birds, since reptiles have the ability to regenerate.^[13]

New species of owl

At the Los Angeles Museum, a collection called Rancho La Brea contains the bones of the Horned Owl which she had noted to be abnormal. The size of the bones could have easily been mistaken for the bones of a variety of North American as well as South American owls. She finds that the fossils resemble closest to Strix even though it is larger than either species that could be found in North America of the genus.^[14] She goes into a full-depth investigation along with evidence filled with measurements and comparisons and finally comes to the conclusion that the bones found in the exhibit were of a new species, which is now named the Strix Brea. She published her findings in The Condor in 1932, naming the entry 'A New Species of Owl from the Pleistocene of Rancho La Brea, California'.^[14]

Contribution to new road-runner species

Located in the Conkling Cavern in Doña Ana County, New Mexico, the remains of extinct mammals were found and were initially hypothesized to be from the Geococcyx californianus.^[15] After comparing the new specimen with the bones of other Geococcyx californius from New Mexico, Arizona and Mexico, Howard observed that none of them are similar in size to the specimen. A year earlier, fossils were discovered two miles away in another cave, whose size was similar to the specimen and exemplified further the dissimilarity with the great roadrunner. Hence, Howard proposed that this specimen be classified as a new species called the Geococcyx conklingi.^[15].