(Type specimen of Eocypselus paulomajor [scale bar = 5 mm], from Mayr and Kitchener, 2024)

Meaning of name: paulomajor = somewhat larger [in Latin]

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: A few forelimb bones of one individual.

Notes: E. paulomajor was a close relative of apodiform birds (the group uniting swifts and hummingbirds). Members of the genus Eocypselus probably looked similar to modern swifts, though they had shorter wings and were better adapted for perching (whereas swifts prefer to cling to vertical surfaces such as cliff faces and tree trunks).

Two species of Eocypselus had previously been named: E. vincenti from England (also from the London Clay Formation) and E. rowei from the United States. Along with the also newly-named E. geminus and E. grandissimus, E. paulomajor suggests that a great diversity of apodiform-like birds lived during the Eocene in what would become the United Kingdom. E. paulomajor was larger than most other species of Eocypselus, but was smaller than E. grandissimus.

Reference: Mayr, G. and A.C. Kitchener. 2024. New fossils of Eocypselus and Primapus from the British London Clay reveal a high taxonomic and ecological diversity of early Eocene swift-like apodiform birds. Ibis advance online publication. doi: 10.1111/ibi.13323

(Type specimen of Pulchrapollia tenuipes, from Mayr and Kitchener, 2023)

Meaning of name: tenuipes = slender foot [in Latin]

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: Partial skeleton of one individual, including two vertebrae and several limb bones.

Notes: P. tenuipes was a halcyornithid, a group of small Eocene birds with two toes pointing forward and two pointing backward on each foot, similar to parrots. In fact, it was once thought that halcyornithids were most closely related to parrots among living birds, but more recent studies suggest that they may have been equally closely related to both parrots and passeriform birds.

The only other species of Pulchrapollia that had been previously named was P. gracilis, which is also known from the London Clay Formation. P. tenuipes differs from P. gracilis in details of the wing and foot bones (including, as its name suggests, in having more slender feet), and its describers only tentatively refer it to the same genus. Along with the also newly-named P. eximia, P. tenuipes suggests that a great diversity of halcyornithids lived during the Eocene in what would become the United Kingdom, with the minor differences among different species perhaps reflecting adaptations to slightly different ecological niches.

Reference: Mayr, G. and A.C. Kitchener. 2023. The Halcyornithidae from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK): a species complex of Paleogene arboreal birds. Geobios advance online publication. doi: 10.1016/j.geobios.2023.06.003

(Type specimen of Pulchrapollia eximia, from Mayr and Kitchener, 2023)

Meaning of name: eximia = extraordinary [in Latin]

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: Partial skeleton of one individual, including much of the skull and parts of all four limbs.

Notes: P. eximia was a halcyornithid, a group of small Eocene birds with two toes pointing forward and two pointing backward on each foot, similar to parrots. In fact, it was once thought that halcyornithids were most closely related to parrots among living birds, but more recent studies suggest that they may have been equally closely related to both parrots and passeriform birds.

The only other species of Pulchrapollia that had been previously named was P. gracilis, which is also known from the London Clay Formation. P. eximia differs from P. gracilis in details of the feet and breastbone, and its describers only tentatively refer it to the same genus. The type specimen of P. eximia includes an exceptionally preserved skull, which has a noticeably smaller braincase than later halcyornithids for which the skull is known.

Along with the also newly-named P. tenuipes, P. eximia suggests that a great diversity of halcyornithids lived during the Eocene in what would become the United Kingdom, with the minor differences among different species perhaps reflecting adaptations to slightly different ecological niches.

Reference: Mayr, G. and A.C. Kitchener. 2023. The Halcyornithidae from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK): a species complex of Paleogene arboreal birds. Geobios advance online publication. doi: 10.1016/j.geobios.2023.06.003

(Type tarsometatarsus [fused ankle and foot bones] of Pristineanis major [scale bar = 5 mm], from Mayr and Kitchener, 2024)

Meaning of name: major = larger [in Latin]

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: A left tarsometatarsus (fused ankle and foot bones).

Notes: P. major appears to have been closely related to piciforms, a group of birds that includes woodpeckers and toucans. Unlike in modern piciforms, the outermost toe on each foot of P. major was probably not fully reversed, but could be rotated into a backward-pointing position. As its name suggests, P. major was larger than the other known species of Pristineanis, P. minor (the type species, also from the London Clay Formation) and P. kistneri (from the Eocene of the western United States, formerly classified in the genus “Neanis”).

Reference: Mayr, G. and A.C. Kitchener. 2024. The Picocoraciades (hoopoes, rollers, woodpeckers, and allies) from the early Eocene London Clay of Walton-on-the-Naze. PalZ advance online publication. doi: 10.1007/s12542-024-00687-9

(Type specimen of Avolatavis europaeus [scale bar = 5 mm], from Mayr and Kitchener, 2023)

Meaning of name: europaeus = from Europe

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: Partial skeleton of one individual, including vertebrae and hindlimb bones.

Notes: The type specimen of A. europaeus had been described briefly in 1998, but was left unnamed as it was held in a private collection instead of a publicly accessible museum at the time. The specimen has since been donated to the National Museums Scotland, allowing for more comprehensive study. The only other species of Avolatavis that had previously been named was the slightly smaller and relatively longer-clawed A. tenens from the Eocene of the United States. A. europaeus thus represents the first record of this genus in Europe.

Avolatavis was originally considered a close relative of parrots, but more recent studies (including this new one) suggest it may have been equally closely related to both parrots and passeriform birds. Nonetheless, its short, stocky feet do bear a close resemblance to those of other Eocene birds that are better supported as members of the parrot lineage. Unlike in modern parrots, the outermost toe on each foot of Avolatavis was probably not fully reversed, but could be rotated into a backward-pointing position.

Reference: Mayr, G. and A.C. Kitchener. 2023. The Vastanavidae and Messelasturidae (Aves) from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Neues Jahrbuch für Geologie und Paläontologie 307: 113–139. doi: 10.1127/njgpa/2023/1119

(Type specimen of Psittacomimus eos [scale bar = 5 mm], from Mayr and Kitchener, 2022)

Meaning of name: Psittacomimus = Psittacus [genus of parrots including the African gray parrot] mimic [in Greek]; eos = dawn [in Greek, referring to its Eocene age]

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: Two partial skeletons, including one that preserves the skull, and a partial right foot. Two other specimens preserving parts of the foot may also belong to this taxon.

Notes: Psittacomimus was a psittacopedid, a group of small Eocene birds that were originally thought to have been closely related to parrots. Like parrots, they had two toes pointing forward and two backward on each foot. However, more recent studies suggest that psittacopedids might have been more closely related to passeriform birds (songbirds and their kin), which instead have the typical condition of modern birds in which three toes face forward and one points back.

The type specimen of Psittacomimus had been previously described briefly in 1998. However, it was left unnamed as it was held in a private collection instead of a publicly accessible museum at the time. The specimen has since been donated to the National Museums Scotland, allowing for more comprehensive study. Psittacomimus was anatomically similar to Parapsittacopes, another psittacopedid known from the London Clay Formation, but was larger than the latter and differs from it in subtle skeletal details, especially in the wing and shoulder bones.

Reference: Mayr, G. and A.C. Kitchener. 2022. Psittacopedids and zygodactylids: the diverse and species-rich psittacopasserine birds from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Historical Biology advance online publication. doi: 10.1080/08912963.2022.2141629

(Skull of Parapsittacopes bergdahli, from Mayr, 2021)

Meaning of name: Parapsittacopes = near Psittacopes [another Eocene bird that was likely a close relative]; bergdahli = for Paul Bergdahl [collector of the original fossil]

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: Partial skeleton of one individual, including the skull and parts of all four limbs.

Notes: Parapsittacopes was likely a psittacopedid, a group of small (wren- to sparrow-sized) Eocene birds that were originally thought to have been closely related to parrots. Like parrots, they had two toes pointing forward and two backward on each foot. However, more recent studies suggest that psittacopedids might have been more closely related to passeriform birds (songbirds and their kin), which instead have the typical condition of modern birds in which three toes face forward and one points back.

Most previously known psittacopedid fossils were preserved as flattened remains, so the three-dimensionally preserved bones of Parapsittacopes reveal several previously unknown psittacopedid features. Some of these features provide further support for placing them as close relatives of passeriforms.

Psittacopedids exhibited a wide variety of beak shapes, and included probable seed-eating and nectar-eating species. The beak of Parapsittacopes was short and slightly widened, a common feature of birds that hunt insects in flight. Parapsittacopes may have caught insects by flying at them from a perch. It might have also fed on fruits.

Reference: Mayr, G. 2021. A remarkably complete skeleton from the London Clay provides insights into the morphology and diversity of early Eocene zygodactyl near-passerine birds. Journal of Systematic Palaeontology advance online publication. doi: 10.1080/14772019.2020.1862930

(Type specimen of Eocypselus grandissimus [scale bar = 5 mm], from Mayr and Kitchener, 2024)

Meaning of name: grandissimus = largest [in Latin]

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: Partial skeleton of one individual including several vertebrae, some forelimb bones, and a pedal phalanx (toe bone).

Notes: E. grandissimus was a close relative of apodiform birds (the group uniting swifts and hummingbirds). Members of the genus Eocypselus probably looked similar to modern swifts, though they had shorter wings and were better adapted for perching (whereas swifts prefer to cling to vertical surfaces such as cliff faces and tree trunks).

Two species of Eocypselus had previously been named: E. vincenti from England (also from the London Clay Formation) and E. rowei from the United States. Along with the also newly-named E. geminus and E. paulomajor, E. grandissimus suggests that a great diversity of apodiform-like birds lived during the Eocene in what would become the United Kingdom. E. grandissimus was noticeably larger than all other known species of Eocypselus.

It is possible that the type specimen of Parvulivenator, a bird from the London Clay Formation known from foot bones, represents a specimen of E. grandissimus, in which case the genus name Eocypselus would need to be replaced by the earlier-named Parvulivenator. (Parvulivenator was originally identified as a small falcon, but there is no strong evidence to support this.) However, there are enough differences between Parvulivenator and Eocypselus species with known foot bones that more specimens are needed to confirm or deny this possibility.

Reference: Mayr, G. and A.C. Kitchener. 2024. New fossils of Eocypselus and Primapus from the British London Clay reveal a high taxonomic and ecological diversity of early Eocene swift-like apodiform birds. Ibis advance online publication. doi: 10.1111/ibi.13323

(Type specimen of Eocypselus geminus [scale bar = 5 mm], from Mayr and Kitchener, 2024)

Meaning of name: geminus = twin [in Latin, referring to its similarity to E. vincenti]

Age: Eocene (Ypresian), 54.6‒55 million years ago

Where found: London Clay Formation, Essex, U.K.

How much is known: Partial skeletons of two individuals, representing part of the skull and multiple limb bones.

Notes: E. geminus was a close relative of apodiform birds (the group uniting swifts and hummingbirds). Members of the genus Eocypselus probably looked similar to modern swifts, though they had shorter wings and were better adapted for perching (whereas swifts prefer to cling to vertical surfaces such as cliff faces and tree trunks).

Two species of Eocypselus had previously been named: E. vincenti from England (also from the London Clay Formation) and E. rowei from the United States. Along with the also newly-named E. grandissimus and E. paulomajor, E. geminus suggests that a great diversity of apodiform-like birds lived during the Eocene in what would become the United Kingdom. E. geminus differed from E. vincenti in minor details of the wing bones, from E. rowei in having relatively longer feet, and from E. grandissimus and E. paulomajor in being noticeably smaller.

Reference: Mayr, G. and A.C. Kitchener. 2024. New fossils of Eocypselus and Primapus from the British London Clay reveal a high taxonomic and ecological diversity of early Eocene swift-like apodiform birds. Ibis advance online publication. doi: 10.1111/ibi.13323

(Tarsometatarsus [fused ankle and foot bones] of Paralyra atavus [scale bar = 10 mm], from Zelenkov, 2024)

Meaning of name: Paralyra = near lyre [in Greek, referencing the extant grouse genus Lyrurus]

Species included: P. atavus (type species, previously in Lagopus)

Age: Pliocene–Pleistocene (Zanclean–Calabrian)

Where found: Rębielice Królewskie 1 and Kielniki 3B, Silesian and Weże 1, Łódź, Poland; Taurida Cave, Crimea, Ukraine; and possibly Muselievo, Pleven, Bulgaria

Notes: Paralyra atavus was a grouse, a group of chicken-like birds found in temperate and cold regions of the Northern Hemisphere. It was formerly classified in the genus Lagopus along with extant ptarmigans, a type of grouse adapted for cold tundra and alpine habitats, and in fact was sometimes considered an extinct subspecies of the willow ptarmigan (L. lagopus). However, newly described specimens from the Pleistocene of Crimea, notably including a complete tarsometatarsus (fused ankle and foot bones), suggest that it was anatomically distinct enough from extant grouse species to be reassigned to a unique genus. Unlike ptarmigans, Paralyra lived in savannah environments.

Reference: Zelenkov, N.V. 2024. Grouse (Aves: Phasianidae: Tetraonini) from the Early Pleistocene of Crimea, and the taxonomic status of Lagopus atavus. Paleontological Journal 58: 112–123. doi: 10.1134/S0031030124010106