The skull of the Miocene Spheniscus urbinai (Aves, Sphenisciformes): osteology, brain morphology, and the cranial pneumatic systems

Spheniscus urbinai represents one of four extinct Spheniscus species from the Cenozoic of southern South America, known from several poorly described diversely complete skulls and postcranial elements. Here, we present a review of the cranial osteology of all known specimens (collected in Argentina,...

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Bibliographic Details
Published in:Journal of anatomy 2021-07, Vol.239 (1), p.151-166
Main Authors: Acosta Hospitaleche, Carolina, Paulina‐Carabajal, Ariana, Yury‐Yáñez, Roberto
Format: Article
Language:English
Subjects:
Animals
Brain - anatomy & histology
Cenozoic
cranial endocast
Endangered & extinct species
Eocene
Extinct species
Miocene
Neogene
Original Paper
Original Papers
osteology
paranasal pneumaticity
Paranasal Sinuses - anatomy & histology
Paranasal Sinuses - diagnostic imaging
paratympanic pneumaticity
penguins
Skull
Skull - anatomy & histology
Skull - diagnostic imaging
skull pneumaticity
South America and Antarctica
Spheniscidae - anatomy & histology
Spheniscus
Tomography, X-Ray Computed
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Summary:Spheniscus urbinai represents one of four extinct Spheniscus species from the Cenozoic of southern South America, known from several poorly described diversely complete skulls and postcranial elements. Here, we present a review of the cranial osteology of all known specimens (collected in Argentina, Chile, and Peru), including a paleoneurological analysis using CT scans, and an exploration of its cranial pneumaticity compared to other extinct and living seabirds. Our results show that among Spheniscus species, S. urbinai exhibits slightly greater cranial pneumaticity than the living species. Additionally, we confirm previous findings which indicate that the marked reduction of cranial pneumaticity—which is characteristic of living penguins—occurred early during the Eocene (as observed in the Antarctic penguin MLP 12‐I‐20‐1, but not in the coeval Anthropornis). We provided new data on the osteology and paleoneurology of Spheniscus urbinai based on the description of eight specimens from the Miocene of Argentina, Chile, and Peru. The analysis of the cranial pneumatic systems in penguins suggests a differential reduction of the pneumaticity during the Eocene toward the recent times.
ISSN:0021-8782
1469-7580
DOI:10.1111/joa.13403