scholarly journals The cranial endocast of the Upper Devonian dipnoan ‘Chirodipterus’ australis

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5148 ◽  
Author(s):  
Struan A.C. Henderson ◽  
Tom J. Challands
Keyword(s):  
Western Australia ◽  
Middle Devonian ◽  
Upper Devonian ◽  
Fine Scale ◽  
Serial Sectioning ◽  
Cranial Cavity ◽  
Basal Position

One of the first endocasts of a dipnoan (lungfish) to be realised was that of the Upper Devonian taxon Chirodipterus australis. This early interpretation was based on observations of the shape of the cranial cavity alone and was not based on a natural cast or ‘steinkern’ nor from serial sectioning. The validity of this reconstruction is therefore questionable and continued reference to and use of this interpretation in analyses of sarcopterygian cranial evolution runs the risk of propagation of error. Here we present a new detailed anatomical description of the endocast of ‘Chirodipterus’ australis from the Upper Devonian Gogo Formation of Western Australia, known for exceptional 3D preservation which enables fine-scale scrutiny of endocranial anatomy. We show that it exhibits a suite of characters more typical of Lower and Middle Devonian dipnoan taxa. Notably, the small utricular recess is unexpected for a taxon of this age, whereas the ventral expansion of the telencephalon is more typical of more derived taxa. The presence of such ’primitive’ characters in ‘C.’ australis supports its relatively basal position as demonstrated in the most recent phylogenies of Devonian Dipnoi.

scholarly journals The cranial endocast of the Upper Devonian dipnoan Chirodipterus australis

2018 ◽  
Author(s):  
Struan A C Henderson ◽  
Tom J Challands
Keyword(s):  
Middle Devonian ◽  
Upper Devonian ◽  
Serial Sectioning ◽  
Cranial Cavity ◽  
Basal Position

One of the first endocasts of a dipnoan (lungfish) to be realised was that of the Upper Devonian taxon Chirodipterus australis. This early interpretation was based on observations of the shape of the cranial cavity alone and was not based on a natural cast or 'steinkern' nor from serial sectioning. The validity of this reconstruction is therefore questionable and continued reference to and use of this interpretation in analyses of sarcopterygian cranial evolution runs the risk of propagation of error. Here we describe a new detailed anatomical description of the endocast of Chirodipterus australis and show that it exhibits a suite of characters more typical of Lower and Middle Devonian dipnoan taxa. Notably, the small utricular recess is unexpected for a taxon of this age, whereas the ventral expansion of the telencephalon is more typical of more derived taxa. The presence of such 'primitive' characters in C. australis supports its relatively basal position as demonstrated in the most recent phylogenies of Devonian Dipnoi.

scholarly journals The cranial endocast of the Upper Devonian dipnoan Chirodipterus australis

2018 ◽  
Author(s):  
Struan A C Henderson ◽  
Tom J Challands
Keyword(s):  
Middle Devonian ◽  
Upper Devonian ◽  
Serial Sectioning ◽  
Cranial Cavity ◽  
Basal Position

One of the first endocasts of a dipnoan (lungfish) to be realised was that of the Upper Devonian taxon Chirodipterus australis. This early interpretation was based on observations of the shape of the cranial cavity alone and was not based on a natural cast or 'steinkern' nor from serial sectioning. The validity of this reconstruction is therefore questionable and continued reference to and use of this interpretation in analyses of sarcopterygian cranial evolution runs the risk of propagation of error. Here we describe a new detailed anatomical description of the endocast of Chirodipterus australis and show that it exhibits a suite of characters more typical of Lower and Middle Devonian dipnoan taxa. Notably, the small utricular recess is unexpected for a taxon of this age, whereas the ventral expansion of the telencephalon is more typical of more derived taxa. The presence of such 'primitive' characters in C. australis supports its relatively basal position as demonstrated in the most recent phylogenies of Devonian Dipnoi.

Paleozoic dipnoan phylogeny: functional complexes and evolution without parsimony

Paleobiology ◽  
1990 ◽  
Vol 16 (2) ◽  
pp. 143-169 ◽  
Author(s):  
K. S. W. Campbell ◽  
R. E. Barwick
Keyword(s):  
Western Australia ◽  
Upper Devonian ◽  
Morphological Data ◽  
Evolutionary Relationships ◽  
New Genera ◽  
Evolutionary Patterns ◽  
Dermal Bones

Attempts at understanding evolutionary relationships among Paleozoic Dipnoi (lungfish) using cladistic methodology have proved totally unsatisfactory (Miles 1977; Marshall 1987). We attempt to reconstruct the relationships between the better known genera using a method that involves the recognition of lineages based on evolving functional complexes, particularly those involved with food reduction and respiration. Within these broadly defined lineages, we have defined sub-lineages based on evolutionary patterns shown by structures that have been stratigraphically dated; such patterns are found inter alia in the roofing bones and the external dermal bones of the mandible. A number of new suborders and families are recognised; genera for which further morphological data are required before they can be assigned to a higher taxon are indicated; two generic synonyms are recognised.In appendices, short descriptions are given of two new genera—Pillararhynchus from the Gogo Formation (Upper Devonian) of Western Australia, and Sorbitorhynchus from the Emsian of Guangxi, China.

Gigantocharinus szatmaryi, a new trigonotarbid arachnid from the Late Devonian of North America (Chelicerata, Arachnida, Trigonotarbida)

2000 ◽  
Vol 74 (1) ◽  
pp. 25-31 ◽  
Author(s):  
William A. Shear
Keyword(s):  
North America ◽  
Middle Devonian ◽  
New Genus ◽  
Upper Devonian ◽  
Late Carboniferous ◽  
Late Devonian ◽  
New Genus And Species ◽  
Significant Time ◽  
The Family ◽  
Time Gap

A new trigonotarbid arachnid, Gigantocharinus szatmaryi new genus and species, is described from Upper Devonian (Late Famennian) sediments in Pennsylvania. Devonian trigonotarbids were known before from only a single North American locality and several European ones. The new trigonotarbid occurs in what had previously been a significant time gap between the faunas of the Middle Devonian and the late Carboniferous. Gigantocharinus szatmaryi is assigned with some hesitation to the family Palaeocharinidae.

An enigmatic blastozoan echinoderm fauna from central kentucky

2009 ◽  
Vol 83 (5) ◽  
pp. 739-749 ◽  
Author(s):  
Colin D. Sumrall ◽  
Carlton E. Brett ◽  
Troy A. Dexter ◽  
Alexander Bartholomew
Keyword(s):  
North America ◽  
Northwest Territories ◽  
Middle Devonian ◽  
Fossil Record ◽  
Foreland Basin ◽  
Late Ordovician ◽  
Upper Devonian ◽  
Range Extension ◽  
First Report ◽  
Appalachian Foreland

A series of small road cuts of lower Boyle Formation (Middle Devonian: Givetian) near Waco, Kentucky, has produced numerous specimens of three blastozoan clades, including both “anachronistic” diploporan and rhombiferan “cystoids” and relatively advanced Granatocrinid blastoids. This unusual assemblage occurs within a basal grainstone unit of the Boyle Limestone, apparently recording a local shoal deposit. Diploporans, the most abundant articulated echinoderms, are represented by a new protocrinitid species, Tristomiocystis globosus n. gen. and sp. Glyptocystitoid rhombiferans are represented by isolated thecal plates assignable to Callocystitidae. Three species of blastoids, all previously undescribed, include numerous thecae of the schizoblastid Hydroblastus hendyi n. gen. and sp., the rare nucleocrinid Nucleocrinus bosei n. sp., and an enigmatic troosticrinid radial. The blastoid Nucleocrinus is typical for the age; however, the callocystitid, schizoblastid, and protocrinitid are not. Hydroblastus is the oldest known schizoblastid. Middle and Upper Devonian callocystitids have been previously reported only from Iowa and Michigan USA with unpublished reports from Missouri USA and the Northwest Territories, Canada. This occurrence is thus the first report of a Middle Devonian rhombiferan from the Appalachian foreland basin. Tristomiocystis is the first known protocrinitid in North America and the only protocrinitid younger than Late Ordovician. This occurrence thus represents a range extension of nearly 50 million years for protocrinids. This extraordinary sample of echinoderms in a Middle Devonian limestone from a well-studied area of North America highlights the incompleteness of the known fossil record, at least in fragile organisms such as echinoderms.

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