 |
ANNAKACYGNA, gen. nov. Annakacygna hajimei and A. yoshiiensis Matsuoka & Hasegawa, 2022 |
Abstract
A new genus and two new species of flightless fossil Cygnini (Aves: Anatidae), Annakacygna hajimei and A. yoshiiensis are described from the horizon of about 11.5 Ma of the Miocene Haraichi Formation, Annaka Group of Gunma, central Japan. The type specimen of A. hajimei (GMNH-PV-678) is the associated skeleton of an adult bird. Osteological features of A. hajimei indicate that this large anatid bird belongs to tribe Cygnini as it possesses the diagnostic features of the tribe such as the long neck and long pelvis with dorsally swelling ala postacetabularis illi. Annakacygna were a group of flightless birds characterized by the distally small wing elements, large body, and pachyostotic bones. In addition, the autapomorphies of Annakacygna indicate that this bird was an animal with the body plan that specialized in breeding behavior, or sex appeal in a broad sense, and uniquely developed the filter feeding with its large head. In a sense, Annakacygna acquired remarkable evolutionary forms for two essential biological activities, eating and reproduction, is the “ultimate bird” ever exist. A. yoshiiensis, known only from the distal end of tibiotarsus (GMNH-PV-1685), was a gigantic species and showed the diversification within this unique genus in the sea of Miocene Japan.
Key Words: Miocene, Annaka Group, Cygnini, Flightless bird, Annakacygna
 |
| The skeleton of Annakacygna hajimei. In standing and wing folded posture. The white elements/parts were not found in the fossil. |
Class AVES Linnaeus, 1758
Order ANSERIFORMES Wagler, 1831
Family ANATIDAE Leach, 1820
Subfamily ANSERINAE Vigors, 1825
Tribe CYGNINI Vigors, 1825
ANNAKACYGNA, gen. nov.
Type Species— Annakacygna hajimei, sp. nov.
Included Species— Type species and A. yoshiiensis, sp. nov.
Diagnosis— Large-sized anatid with a relatively big head and relatively reduced pectoral skeleton that is characterized by the
combination of the following osteological features: craniumwide fossa temporalis, presence of "pseudo-sagittal crest",
presence of salt gland impression; lacrimal- unfused to the frontal
of ...
Etymology— Combination of Annaka, the city name of type locality, and cygna, the feminine of Latin cygnus, swan.
ANNAKACYGNA HAJIMEI, sp. nov.
Etymology— After local paleontologist Mr. Hajime Nakajima,
in recognition of his outstanding contributions to vertebrate
paleontology of Gunma.
Etymology— After the name of type locality town, Yoshiimachi.
MATSUOKA Hiroshige and HASEGAWA Yoshikazu. 2022. Annakacygna, A New Genus for Two remarkable Flightless Swans (Aves, Anatidae, Cygnini) from the Miocene of Gunma, central Japan: With A Note on the Birds’ food niche shift and Specialization of Wings for parental care actions. Bull. Gunma Mus. Natu. Hist. (26); 1-30 www.gmnh.pref.gunma.jp/research/no26/
twitter.com/albertonykus/status/1518579679850029063
