| Waltonavis | |
|---|---|
 | |
| Fossil material ofWaltonavis spp. | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Clade: | Coraciimorphae |
| Clade: | Cavitaves |
| Order: | Leptosomiformes (?) |
| Genus: | †Waltonavis Mayr & Kitchener,2022 |
| Type species | |
| †Waltonavis paraleptosomus Mayr & Kitchener, 2022 | |
| Otherspecies | |
Waltonavis (meaning "Walton bird") is an extinct genus of potentiallyleptosomiform bird from theEarly EoceneLondon Clay Formation ofEssex, United Kingdom. The genus contains two species:W. paraleptosomus andW. danielsi, both known from partial skeletons.[1]
Waltonavis wasdescribed in 2022 by German paleontologistGerald Mayr and British zoologistAndrew C. Kitchener. Thegeneric name, "Waltonavis", combines a reference to the type locality with theLatin word "avis", meaning "bird". The type species,W. paraleptosomus, was described on the basis of a partial skeleton collected in 1988. This specimen,NMS.Z.2021.40.16, which includes the leftquadrate andpterygoid, a partial leftscapula, a leftcoracoid, the cranial portion of thesternum, and a left and partial righttarsometatarsus, was designated as theholotype. NMS.Z.2021.40.17—19, additional specimens collected in 1996, 1983, and 1988, respectively, include more fossil material, including the remains of a juvenile individual. They were also referred toW. paraleptosomus. These fossils were discovered by Michael Daniels in layers of theLondon Clay Formation (Walton Member), dated to the earlyYpresian, which is located nearWalton-on-the-Naze in Essex, England. Thespecific name, "paraleptosomus", is derived from theGreek “παρα” (“para”) and the name of the extant birdLeptosomus, in reference to similarities between the bones of the two taxa.[1]
Additional fossil material collected in 1985 was assigned to a separate species ofWaltonavis,W. danielsi. The holotype ofW. danielsi,NMS.Z.2021.40.20, consists of several vertebrae, the right coracoid, a partial right scapula, a righthumerus, a partial left humerus, a rightulna, a partial left ulna, a leftcarpometacarpus, partialphalanges, a partial rightfemur, a partial righttibiotarsus, and a partial left tarsometatarsus. The specific name, “danielsi” honors Michael Daniels, the discoverer of the holotype.[1]
Several additional fragmentary skeletons collected in the late 1900s by Daniels were assigned toWaltonavis, but they lack sufficient material to be assigned to eitherW. paraleptosomus orW. danielsi.[1]
Waltonavis was similar in size and morphology toLapillavis, an extinct bird from the mid-EoceneMessel pit of Germany. It also shows several similarities to the larger extantLeptosomus, which feeds on large insects and small reptiles. Due to differences in beak and wing bone shape,Waltonavis likely had feeding habits distinct fromLeptosomus.[1]
Mayr and Kitchener (2022) noted several similarities betweenWaltonavis andleptosomiforms. They suggested that an assignment to the Leptosomiformes is likely, but that a unique combination of features makes precise classification difficult. The cladogram below displays the relation ofWaltonavis withinTelluraves.[1]
