Agapornis atlanticus, Mourer-Chauviré & Geraads, 2010
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publication ID |
https://doi.org/ 10.3853/j.0067-1975.62.2010.1538 |
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persistent identifier |
https://treatment.plazi.org/id/4C1D87C7-962D-DA5E-FC3D-FB1DFB18FC5A |
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treatment provided by |
Marcus |
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scientific name |
Agapornis atlanticus |
| status |
sp. nov. |
Agapornis atlanticus n.sp.
Fig. 5N–Q View Figure 5
Holotype. Almost complete right humerus AaO-786.
Horizon and locality. Late Pliocene, age about 2.5 Ma, Ahl al Oughlam, southeast boundary of the city of Casablanca, Morocco.
Paratypes. Incomplete right humeri, AaO-788, 789, 791, 2670; right humeri, proximal part, AaO-784, 790, 793, 800; right humeri, distal part, AaO-794, 2700, 2701, 2702, 4812; left humeri, AaO-785, 2671; left humeri, almost complete, AaO-783, 787, 853, 854; left humeri, distal part, AaO-2703, 2704, 2705, 2706. The humeri AaO-790, 794, 2700, and 4812 show a deposit of medullary bone.
Referred material. Right ulnae, proximal part and shaft, AaO-797, proximal part, AaO-4814; right ulnae, distal part, AaO-799, 4816; left ulna, almost complete, AaO-792; left ulnae, proximal part, AaO-795, 796, 4815; left ulna, distal part, AaO-4817; right carpometacarpi, almost complete, AaO-775, 776, 778; right carpometacarpus, proximal part, AaO-798; left carpometacarpi, proximal part, AaO-779, 4813.
Diagnosis. Species larger than the Recent or fossil species of the genus Agapornis . The humeral head shows a distal extension on the caudal face. On the dorsal side of
n.sp., from Ahl al Oughlam, and that of a Recent specimen of Agapornis taranta, USNM 322302.
the humeral head there is a longitudinal ridge which is more developed than in the Recent species.
Measurements. See Table 10.
Etymology. atlanticus , from the Atlantic Ocean, because the locality of Ahl al Oughlam was on the Atlantic shore at the time of the deposit.
Curation of the material. The material will be deposited at the Institut National des Sciences de l’Archéologie et du Patrimoine (INSAP), in Rabat, Morocco.
Description and comparisons. These parrot specimens have been compared with all of the genera that occur in Africa at the present time and which are present in the USNM collection. The fossils can be attributed to the genus Agapornis . Among the Recent species of this genus there is a size variation, the smallest one being A. lilianae , then by increasing size A. pullarius , A. personatus , A. fischeri , A. roseicollis , and A. taranta . There was no comparative skeleton of A. nigrigenis but this species is similar in size to A. lilianae . The Ahl al Oughlam Agapornis remains are large and, by their dimensions, they are closer to the Recent species A. taranta . Compared to a sample of six individuals of A. taranta , the total length of the humerus is similar, but the distal width is smaller and the width of the shaft in the middle is larger in the Moroccan form. In the ulna the mean values of the proximal width and width of shaft in the middle are larger, and for the carpometacarpus the total length and the proximal depth are also larger in the Ahl al Oughlam species.
Morphologically the humerus of Agapornis atlanticus differs from the Recent species by the presence of a distal extension of the humeral head on the caudal face. This extension does not exist in the Recent Agapornis . There is also a longitudinal ridge that begins on the dorsal side of the humeral head and extends distad. It delimits an elongate fossa, situated between this ridge and the crista m. supracoracoidei. This ridge is very faintly visible in the Recent Agapornis ( Fig. 6 View Figure 6 ). At the distal end, the attachment of the anterior articular ligament is strongly projecting. Proximal to this attachment, the impression of M. brachialis is situated entirely on the ventral half of the bone. There is a tubercle proximal to the dorsal condyle but it is very slightly indicated and it is visible only on one half of the humeri. This characteristic is different from that described by Stidham for the Recent and fossil Agapornis from South Africa, where “the humeri exhibit the character of having a tubercle proximal to the space in between the dorsal and the ventral condyles” ( Stidham, 2006, p. 199). In the Ahl al Oughlam parrots the dorsal condyle measures about 2.5 mm proximodistally and the tubercle is situated about 1 mm proximally to the condyle. This position is different from what we have observed in the genus Poicephalus where a tubercle is present and situated proximally to the dorsal condyle, but on the median side of this condyle and closer to it.
Extinct psittacids exist in the Neogene of the Palaearctic region, such as Archaeopsittacus verreauxi , from the early Miocene of Saint-Gérand-le-Puy (MN 2a) ( Milne-Edwards, 1867 –1871), Xenopsitta fejfari from the early Miocene of Merkur (MN 3) ( Mlíkovský, 1998a), and Pararallus dispar (syn. Psittacus lartetianus ) from the middle Miocene of Sansan (MN 6) ( Cheneval, 2000). Indeterminate psittacids have also been reported in the middle Miocene of the Nördlinger Ries (MN 6) and of Steinheim (MN 7) (Heizmann & Hesse, 1995). In Africa, psittacids were present in the late Miocene and the early Pliocene of Langebaanweg ( Rich, 1980; Stidham, 2006), and Agapornis sp. is reported from two localities of Olduvai, Bed I, lower Pleistocene ( Brodkorb, 1985), and from the Pleistocene of Kromdraai B ( Stidham, 2006).
The presence of an Agapornis species in Morocco is surprising because all of the Recent species of this genus live South of the Sahara, and most of them have a very limited distribution area in the southern part of the African continent. These different species live in variable environments, moist savannah, lowland primary and secondary forests, montane forests, wooded steppe ( Fry et al., 1988), but one species, A. roseicollis , lives close to the western coast of Southern Africa ( Angola, Namibia, South Africa) in dry wooded and subdesert steppe. This species may sometimes nest in rock crevices. The presence of medullary bone ( Rick, 1975) inside the medullary cavity of several humeri indicates that Agapornis atlanticus was nesting in the vicinity of the fossiliferous site. It it possible that this species nested in the blocks of consolidated sands in which the fossils were deposited, while the other species of this genus nest in termitaria or in trees ( Fry et al., 1988).
Order Strigiformes
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