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A partial skeleton of Septencoracias reveals derived features of bee-eaters (1 Viewer)

Fred Ruhe

Well-known member
Netherlands
Gerald Mayr, 2021

A partial skeleton of Septencoracias from the early Eocene London Clay reveals derived features of bee-eaters (Meropidae) in a putative stem group roller (Aves, Coracii)

Palaeobiodiversity and Palaeoenvironments;
doi: 10.1007/s12549-021-00504-0

Free pdf: https://link.springer.com/content/pdf/10.1007/s12549-021-00504-0.pdf

Abstract:

A partial skeleton of the putative stem group roller Septencoracias is described from the early Eocene London Clay of Waltonon-the-Naze (Essex, UK). With an age of about 55 million years, the bones represent one of the earliest fossil records of a coraciiform bird. The new fossil reveals that the proximal pedal phalanges of the three anterior toes of Septencoracias exhibit markedly widened distal ends. This distinctive trait is not found in other representatives of the Coracii, but occurs in the Meropidae (bee-eaters). The quadrate likewise exhibit a derived characteristic of the Meropidae, and the beak is narrower than in rollers. These previously unnoticed features are of particular interest, because the Meropidae result as the sister taxon of the Coracii in sequence-based analyses. Calibrated molecular data suggest that the divergence between the Coracii and the Meropidae occurred at 55.6 Ma, with the new fossil being only slightly younger than this date. However, phylogenetic analyses recovered Septencoracias within the Coracii, so that the derived features shared with the Meropidae most likely are either plesiomorphic and were lost in the Coracii, or they represent parallelisms that evolved convergently in Septencoracias and the Meropidae. In any case, these traits suggest that Septencoracias differed from extant rollers in its ecological preferences and foraging mode

Enjoy,

Fred
 

Fred Ruhe

Well-known member
Netherlands
Systematic palaeontology

Aves Linnaeus, 1758
Coraciiformes Forbes, 1884
?Coracii Wetmore and Miller, 1926
Septencoracias Bourdon, Kristoffersen et Bonde, 2016.

Emended diagnosis: In addition to the characters listed by Bourdon et al. (2016), the taxon Septencoracias is diagnosed by widened distal sections of the proximal phalanges of the three anterior toes.

Septencoracias cf. morsensis Bourdon, Kristoffersen et Bonde, 2016.

Referred specimen: SMF Av 655: partial skeleton including large portions of the mandible, the left jugal arch, left quadrate, nine vertebrae or fragments thereof, right carpometacarpus distal section of right radius, nearly complete right tibiotarsus, distal section of left tibiotarsus, right fibula, fragment of left trochlea metatarsi IV, and most pedal phalanges of the left foot (Fig. 1); the fossil was found in 1988 by Paul Bergdahl (original collector’s number BC 8813).

Locality and horizon: Walton-on-the-Naze, Essex, UK; Walton Member of the London Clay Formation (previously Division A2; Jolley 1996; Aldiss 2012), early Eocene (early Ypresian; 54.6–55 Ma; Collinson et al. 2016).

Measurements (length in mm; in brackets the dimension of the Septencoracias morsensis holotype; after Bourdon et al. 2016): Mandible, length as preserved, 36.9 [48.5]. Carpometacarpus, 18.1 [17.2/18.0]. Tibiotarsus, 29.0 [30.9]. Pedal phalanges, I1: 7.0 [8.3]; II1, 5.0 [5.4]; II2, 5.1 [5.1]; III1, 5.1 [5.4]; III2, 5.0 [5.2]; III3, 5.6 [5.7]; IV1, 3.3 [4.3]; IV2/IV3, 3.2 [3.7/3.5]; IV4, 4.3 [4.2], ungual phalanx, > 4.2

Fred


Fig. 1 Septencoracias cf. morsensis from the early Eocene London Clay of Walton-on-the-Naze (SMF Av 655), major bones preserved in the specimen. a Mandible in ventral view. b Left jugal arch. c Caudal end of the left mandibular ramus in ventral view. d Partial left quadrate. e Cervical vertebra. f, g Cervicothoracic vertebrae. h, i Thoracic vertebrae. j Caudal vertebra. g Distal section of right radius. l Right carpometacarpus. m Right tibiotarsus. n Distal portion of left tibiotarsus. o Right fibula. p Fragment of left trochlea metatarsi IV and pedal phalanges of left foot.
Scale bar equals 5 mm
 

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