Osteichthyan-like cranial conditions in an Early Devonian stem gnathostome

@article{Giles2015OsteichthyanlikeCC,
  title={Osteichthyan-like cranial conditions in an Early Devonian stem gnathostome},
  author={Sam Giles and M. Friedman and Martin D. Brazeau},
  journal={Nature},
  year={2015},
  volume={520},
  pages={82 - 85}
}
The phylogeny of Silurian and Devonian (443–358 million years (Myr) ago) fishes remains the foremost problem in the study of the origin of modern gnathostomes (jawed vertebrates). A central question concerns the morphology of the last common ancestor of living jawed vertebrates, with competing hypotheses advancing either a chondrichthyan- or osteichthyan-like model. Here we present Janusiscus schultzei gen. et sp. nov., an Early Devonian (approximately 415 Myr ago) gnathostome from Siberia… Expand
Neurocranial anatomy of an enigmatic Early Devonian fish sheds light on early osteichthyan evolution
TLDR
A second skull of ‘Ligulalepis’ is described and micro-CT data is presented to reveal novel anatomical features, including cranial endocasts, which are shown to be variable in its development between specimens. Expand
An exceptionally preserved Late Devonian actinopterygian provides a new model for primitive cranial anatomy in ray-finned fishes
TLDR
An exceptionally preserved ray-finned fish from the Late Devonian (Middle Frasnian, ca 373 Ma) of Pas-de-Calais, northern France is presented, representing by a single, three-dimensionally preserved skull, with no support found for a monophyletic grouping of Moythomasia with Mimiidae. Expand
A symmoriiform from the Late Devonian of Morocco demonstrates a derived jaw function in ancient chondrichthyans
TLDR
A previously undescribed symmoriiform shark, Ferromirum oukherbouchi, from the Late Devonian of the Anti-Atlas is reported, in which the jaw articulation is specialized and drives mandibular rotation outward when the mouth opens, and inward upon closure. Expand
A new osteichthyan from the late Silurian of Yunnan, China
TLDR
A phylogenetic analysis resolves Sparalepis within a previously recovered cluster of stem-sarcopterygians including Guiyu, Psarolepis and Achoania, suggesting that the South China block may have been an early center of diversification for early gnathostomes, well before the advent of the Devonian “Age of Fishes”. Expand
Questioning hagfish affinities of the enigmatic Devonian vertebrate Palaeospondylus
TLDR
New tomographic data reveal that the following characters of crown-group gnathostomes (chondrichthyans + osteichthyans) are present in Palaeospondylus: a longer telencephalic region of the braincase, separation of otic and occipital regions by the otico-occipital fissure, and vertebral centra. Expand
Endocast and Bony Labyrinth of a Devonian “Placoderm” Challenges Stem Gnathostome Phylogeny
TLDR
The results call into question the appropriateness of arthrodire-like placoderms as models of primitive gnathostome anatomy and raise questions of homology relating to key cranial features. Expand
A new stem sarcopterygian illuminates patterns of character evolution in early bony fishes
TLDR
A new lobe-finned fish Ptyctolepis brachynotus dating from the Early Devonian is described, which preserves a novel combination of cranial characters and suggests revision of evolutionary relationships among bony fish. Expand
The Oldest Actinopterygian Highlights the Cryptic Early History of the Hyperdiverse Ray-Finned Fishes
TLDR
Phylogenetic analysis places Meemannia as an early-diverging ray-finned fish, resolving it as the sister lineage of Cheirolepis plus all younger actinopterygians, and fills a conspicuous faunal gap in the otherwise diverse late Silurian-earliest Devonian vertebrates of the South China Block. Expand
Endocast and bony labyrinth of a stem gnathostome shed light on the earliest diversification of jawed vertebrates
TLDR
The endocranial cavity and inner ear of Brindabellaspis stensioi is described, commonly recovered as a taxon of uncertain affinity branching near the base of ‘placoderms’, and its results call into question the appropriateness of fusiform ’placoderm’ as models of primitive gnathostome anatomy and raise questions of homology relating to key cranial features. Expand
Endoskeletal structure in Cheirolepis (Osteichthyes, Actinopterygii), An early ray‐finned fish
TLDR
Re‐examinations of existing museum specimens through the use of high‐resolution laboratory‐ and synchrotron‐based computed tomography scanning reveal new details of the neuro‐cranium, hyomandibula and pectoral fin endoskeleton for the Eifelian Cheirolepis trailli, helping clarify primitive conditions within ray‐finned fishes. Expand
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 41 REFERENCES
A Silurian placoderm with osteichthyan-like marginal jaw bones
TLDR
A three-dimensionally preserved 419-million-year-old placoderm fish from the Silurian of China is described that represents the first stem gnathostome with dermal marginal jaw bones (premaxilla, maxilla and dentary), features previously restricted to Osteichthyes. Expand
Acanthodes and shark-like conditions in the last common ancestor of modern gnathostomes
TLDR
A new description of the Acanthodes braincase is presented, yielding new details of external and internal morphology, notably the regions surrounding and within the ear capsule and neurocranial roof that contribute to a new reconstruction that, unexpectedly, resembles early chondrichthyan crania. Expand
A PRIMITIVE CHONDRICHTHYAN BRAINCASE FROM THE EARLY DEVONIAN OF SOUTH AFRICA
Abstract The earliest-known chondrichthyan braincase, from the Early Devonian (Emsian) Gydo Formation of South Africa, is described along with parts of the visceral skeleton. Only the ventral surfaceExpand
The braincase and jaws of a Devonian ‘acanthodian’ and modern gnathostome origins
TLDR
The first-known braincase of an Early Devonian acanthodian is presented, andylogenetic analysis resolves Ptomacanthus as either the most basal chondrichthyan or as the sister group of all living gnathostomes, to provide a more detailed picture of the acquisition of early Gnathostome characters. Expand
A PRIMITIVE ACTINOPTERYGIAN NEUROCRANIUM FROM THE EARLY DEVONIAN OF SOUTHEASTERN AUSTRALIA
TLDR
This specimen is the first early osteichthyan to demonstrate the presence of an eyestalk, previously known only in placoderms and chondrichthyans. Expand
An enigmatic gnathostome vertebrate skull from the Middle Devonian of Bolivia.
TLDR
No character clearly supports affinities of R. boliviana to any of the currently known major gnathostome groups, but tenuous hints suggest a relationship to the enigmatic fossil Zamponiopteron, known by peculiar calcified ‘fin plates’ and isolated shoulder girdles. Expand
The characters of Palaeozoic jawed vertebrates
TLDR
A clearly stated hierarchy of synapomorphies covering the jaw-bearing stem gnathostomes and osteichthyan and chondrichthyan stem groups is provided and a proposed synapomorphy scheme is used to evaluate the status of the problematic fossil groups Acanthodii and Placodermi. Expand
The braincase of the chondrichthyan Doliodus from the Lower Devonian Campbellton Formation of New Brunswick, Canada
TLDR
Doliodus has curious bar-like, paired subcranial ridges ending posteriorly at the hyomandibular articulation, adding circumstantial palaeontological support to the old proposal that parts of visceral arches may be incorporated into the gnathostome braincase, although it seems more plausible that they formed in the lateral margins of the embryonic parachordal or hypotic lamina. Expand
BRAINCASE OF THE UPPER DEVONIAN SHARK CLADODOIDES WILDUNGENSIS (CHONDRICHTHYES, ELASMOBRANCHII), WITH OBSERVATIONS ON THE BRAINCASE IN EARLY CHONDRICHTHYANS
Abstract The braincase of an Upper Devonian shark (Cladodoides wildungensis) is investigated using high-resolution CT scanning, and its internal and external morphology is described fromExpand
Jaws and teeth of the earliest bony fishes
TLDR
Andreolepis and Lophosteus are not only the oldest but also the most phylogenetically basal securely identified osteichthyans known so far, indicating that they can be assigned to the stem group. Expand
...
1
2
3
4
5
...