Name: Richard Santos Buchmann de Oliveira
Type: PhD thesis
Publication date: 29/11/2022
Advisor:

Name	Role
Taissa Rodrigues Marques da Silva	Advisor *

Examining board:

Name	Role
Alexandre Liparini Campos	External Examiner *
Fabiana Rodrigues Costa Nunes	External Examiner *
Felipe Chinaglia Montefeltro	External Examiner *
Felipe Lima Pinheiro	External Examiner *
Gabriel de Souza Ferreira	External Alternate *
Roberta Paresque	Internal Alternate *
Taissa Rodrigues Marques da Silva	Advisor *

Summary: Pterosaurs and birds are winged archosaurs that originated in the Mesozoic. Flight
allowed representatives of both clades to explore previously vacant niches, and the
differentiation of forelimbs into wings made the neck of these animals an active,
functional limb used during foraging. Presently, birds have diversified and have necks of
varying lengths, which are adapted to different life habits. However, the lack of extant
descendants of pterosaurs creates gaps in the knowledge regarding the biology of this
group, including its cervical anatomy and biomechanics. Here, we identify and describe
the vertebral arrangement and influence of cervical soft tissues on the neck position at
rest of extant birds. We then apply this data to establish and infer the neck position at rest
and associated cervical soft tissues, and quantify the likely movements performed by the
neck musculature of pterosaurs. For that end, we dissected the necks of specimens
representing sixteen species of extant birds and used computed tomography scans of the
cervical series of the pterosaurs Anhanguera piscator, Azhdarcho lancicollis and
Rhamphorhynchus muensteri with three-dimensional preservation of the largest number
of vertebral elements. We inferred the cervical muscles forces for pterosaurs by
multiplying the thickness of the widest point of the muscle and its stress value. We found
that the thickness of the intervertebral cartilage of extant birds varies along the neck and
that excluding it can distort reconstructions of the neck of extinct animals. We also
recognized sixteen muscles associated with the neck of extant birds. The vertebrae of
extant archosaurs and pterosaurs showed evolutionary convergences that allowed us to
reconstruct synovial cartilages in joints and ligaments in the latter. According to the
angulation of the cervical vertebrae, the pterosaur neck probably had a slightly sinuous
shape when in a rest position. Furthermore, we inferred thirteen cervical muscles in
pterosaurs. We conclude that in pterosaurs the musculature responsible for the
dorsoventral movements of the skull and neck was probably more robust and stronger, as
in extant birds, and that less robust muscles were associated with stabilizing the neck or
performing additional force for cervical movements.
Key words: Cervical vertebrae, Pterosauria, Birds, Aequolitornithes, Cervical muscles,
Cervical ligaments.