Neurocranial anatomy of an enigmatic Early Devonian fish sheds light on early osteichthyan evolution

• Published in: eLife Vol. 7
• Main Authors: Clement, Alice M, King, Benedict, Giles, Sam, Choo, Brian, Ahlberg, Per E, Young, Gavin C, Long, John A
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 29.05.2018; eLife Sciences Publications, Ltd; eLife Sciences Publications Ltd
• Subjects: Animals; Australia; Bayes Theorem; Biological Evolution; Braincase; Computed Tomography; Devonian; Devonian period; Ear, Inner - anatomy & histology; Ear, Inner - diagnostic imaging; Ear, Inner - physiology; Evolutionary Biology; Extinction, Biological; Fishes - anatomy & histology; Fishes - classification; Fishes - physiology; Fossils; Fossils - anatomy & histology; Fossils - diagnostic imaging; Fossils - history; History, Ancient; Ligulalepis; Natural history; Novels; Osteichthyes; Phylogeny; Physiological aspects; Prehistory; Scientists; Skull - anatomy & histology; Skull - diagnostic imaging; Skull - physiology; Vertebrates; X-Ray Microtomography; Australia; Devonian; genetics; Braincase; genomics; Computed Tomography; Phylogeny; Ligulalepis; Osteichthyes
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.34349

The skull of ' ' from the Early Devonian of Australia (AM-F101607) has significantly expanded our knowledge of early osteichthyan anatomy, but its phylogenetic position has remained uncertain. We herein describe a second skull of ' ' and present micro-CT data on both specimens to reveal novel anatomical features, including cranial endocasts. Several features previously considered to link ' with actinopterygians are now considered generalized osteichthyan characters or of uncertain polarity. The presence of a lateral cranial canal is shown to be variable in its development between specimens. Other notable new features include the presence of a pineal foramen, the some detail of skull roof sutures, the shape of the nasal capsules, a placoderm-like hypophysial vein, and a chondrichthyan-like labyrinth system. New phylogenetic analyses place ' ' as a stem osteichthyan, specifically as the sister taxon to 'psarolepids' plus crown osteichthyans. The precise position of 'psarolepids' differs between parsimony and Bayesian analyses.