Perplexicervix sp.

Mayr, Gerald, Carrió, Vicen & Kitchener, Andrew C., 2023, On the “ screamer-like ” birds from the British London Clay: An archaic anseriform-galliform mosaic and a non-galloanserine “ barb-necked ” species of Perplexicervix, Palaeontologia Electronica (a 33) 26 (2), pp. 1-23 : 16-18

publication ID	https://doi.org/ 10.26879/1301
publication LSID	lsid:zoobank.org:pub:7C46BBEC-EEDC-4EF1-B821-9284F9BA8408
persistent identifier	https://treatment.plazi.org/id/03AF87E9-FF91-2F2D-FE1D-F92E1127C9E7
treatment provided by	Felipe
scientific name	Perplexicervix sp.
status

Treatment

Perplexicervix sp.

Referred specimens. NMS.Z.2021.40.9 ( Figure 7D View FIGURE 7 ; caudal portion of right mandibular ramus,

fourth or fifth cervical vertebra, pygostyle). NMS.Z.2021.40.10 ( Figure 7E View FIGURE 7 ; third cervical vertebra).

Remarks. The caudal portion of the mandible of NMS.Z.2021.40.9 ( Figure 8N View FIGURE 8 ) exhibits a morphology characteristic of neoavian birds and is very different from the caudal mandible of Danielsavis and other galloanserines, in which there are two shallow cotylae that are separated by a longitudinal ridge running in parallel to the main axis of the mandible. The cotyla caudalis of Perplexicervix is pronounced, whereas it is absent in galloanserine birds, whose quadrates lack a condylus caudalis. In further contrast to Danielsavis and other Galloanseres, the mandible lacks a retroarticular process.

The two cervical vertebrae preserved in the specimens have a tuberculate surface ( Figure 8O, P View FIGURE 8 ), but are smaller than the cervicals of the P. paucituberculata holotype ( Figure 7A, D, E View FIGURE 7 ). The pygostyle of NMS.Z.2021.40.9 ( Figure 7D View FIGURE 7 ) differs from that of the P. paucituberculata holotype in that the caudoventral portion of the corpus is perforated by a foramen.

Aves indet. A

Referred specimens. NMS.Z.2021.40.5 ( Figure 10A View FIGURE 10 ; partial skeleton including right quadrate, two cervical vertebrae, cranial portion of left scapula, carpal bones and wing phalanges, distal end of left tarsometatarsus, pedal phalanges). NMS.Z.2021.40.8 ( Figure 10B, C View FIGURE 10 ; partial left tarsometatarsus, pedal phalanges; the specimen was erroneously labeled as NMS.Z.2021.40.4 by Houde et al., 2023: figure 6E based on a mislabeled image provided by M. Daniels [P. Houde, pers. comm. in review]).

Remarks. These two specimens were assigned to “group B” by Houde et al. (2023) and represent a species that was smaller than Perplexicervix paucituberculata . Houde et al. (2023) noted that the quadrate associated with NMS.Z.2021.40.5 ( Figure 10E‒H View FIGURE 10 ) exhibits three condyles, which precludes its assignment to the Galloanseres. The authors hypothesised that the bone may have been erroneously associated with the specimen, but in size it corresponds well to the other bones and there exists no indication that it was misplaced (even though we cannot conclusively exclude this possibility).

Unlike in Danielsavis nazensis and P. paucituberculata , the third cervical vertebra has an osseous bridge from the processus transversus to the zygapophysis caudalis, which delimits a small lateral foramen. The surfaces of the two cervical vertebrae preserved in NMS.Z.2021.40.5 lack tubercles. The acromion of the scapula is proportionally longer than in Perplexicervix . The tarsometatarsus is longer than that of Danielsavis. The hypotarsus is damaged, but does not seem to exhibit canals or sulci ( Figure 10M View FIGURE 10 ). Unlike in Danielsavis, the plantar articulation surface of the trochlea metatarsi III is not asymmetric.

Aves indet. B

Referred specimen. NMS.Z.2021.40.4 ( Figure 10D View FIGURE 10 ; partial skeleton including pterygoid, atlas and cervical vertebra, proximal and distal ends of right ulna, proximal and distal ends of right carpometacarpus, both ulnar carpal bones, distal end of right femur, distal end of right tarsometatarsus in a piece of matrix, pedal phalanges).

Remarks. This fossil was also assigned to “group B” by Houde et al. (2023), but is distinctly smaller than the specimens we refer to Aves indet. A ( Figure 10 K, L View FIGURE 10 ). The pterygoid ( Figure 10I, J View FIGURE 10 ) lacks a facies articularis basipterygoidea, which shows the fossil to be outside Galloanseres and also precludes possible affinities to Perplexicervix (because the skull of P. microcephalon from Messel does have basipterygoid processes). As in Aves indet. A, but unlike in P. paucituberculata , the third cervical vertebra exhibits an osseous bridge from the processus transversus to the zygapophysis caudalis, which delimits a small lateral foramen.