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A full description of a complete and articulated, three-dimensionally preserved, placoderm fish, Materpiscis attenboroughi (Ptyctodontida), from the Late Devonian Gogo Formation is presented. The jaw articulation is unique in being preserved in situ, providing new morphological information on the articulation of the quadrate, metapterygoid, and labial skeleton. In addition, separate hyoid and opercular cartilages are identified, thus confirming their presence for the first time within placoderms. Preserved orbital ossifications indicate an anteriomesial orientation of this braincase region. The complete scapulocoracoid provides additional morphological information on the pectoral fin articulation. A new specimen of Austroptyctodus gardineri preserving the anterior portion of the head and jaws allows for revised descriptions of the endocranium and visceral skeleton, including the most complete endocranial ossifications recovered to date. As well, elements of the labial skeleton not known previousl...

A new holodontid lungfish, Xeradipterus hatcheri, gen. et sp. nov., is described from the Late Devonian (Frasnian) Gogo Formation, Western Australia. The material comprises a single specimen preserved in a large concretion, represented by elements of the skull roof, cheek, lower jaw, palate, shoulder girdle, and parts of the postcranial skeleton. Xeradipterus, gen. nov., differs from other holodontids by its broad crushing dentition, prearticular tooth plates with pronounced heel, lack of prominent teeth, and ordered tooth rows, and by its parasphenoid morphology. Results of PAUP analyses of 82 characters for 33 dipnoan taxa revealed that the new genus is a member of the Holodontidae, suggesting a possible endemic radiation of holodontids within the Gogo fauna. In addition, new “Holodipterus” elderae material examined shows the shape and extent of the nasal capsules, and the presence of an anterior median callus for the first time.

Examining morphological patterns is key to understanding mechanics and function in biological systems. In extinct taxa, there is a lack of observational or behavioral data to use to understand function, and groups without descendants limit the use of modern homologues. The only available evidence for function is the morphological characteristics of the preserved fossils. The purpose of this research is to analyze the functional consequences of variation in the lower jaw morphology in Late Devonian arthrodire placoderms. Landmark-based morphometric data were collected for 94 isolated arthrodire inferognathals (lower jaws) from the Gogo Formation in Western Australia and the Cleveland Shale in Ohio. These data were used to define the morphological differences and variation between two phylogenetically distinct morphotypes. Statistical results indicate fundamental shape differences between the two arthrodire morphotypes (coccosteomorphs and pachyosteomorphs). Differences in the shape of the blade po...

Compagopiscis croucheri and Gogopiscis gracilis (Gardiner and Miles, 1994) were collected in high numbers and in different size classes from the Upper Devonian Gogo Formation, Western Australia. This material has provided the basis for an investigation of ontogentic and phenotypic variation of characters and their phylogenetic implications. We used the Principal Component Analysis to examine if variation between specimens assigned to C. croucheri and G. gracilis could be attributed to random variation. In our analysis we found that only the first two principal components showed any significant ability to discriminate between the specimens assigned to C. croucheri and G. gracilis. The first principal component is a measure of overall size of the specimen, so that variation in this principal component can be explained in terms of maturity and growth within a single species. Not all the anatomical variation observed in this study can be attributed to ontogeny and it is considered that the two-class ...

The Late Devonian Gogo Formation of Western Australia has pro vided a wealth of new anatomical information about basal gnathostome fishes, particularly about the nature of early sarcopterygians (Miles, 1977; Campbell and Barwick, 1999; Long et al., 1997). New discov eries from Gogo of an as yet undescribed species of the osteichthyan Onychodus (Jessen, 1966; Fig. 1) show for the first time the structure of the braincase and other features which provide information concern ing the possible origin of the group. Recent discoveries of Psarolepis romeri, a primitive bony fish from the Late Silurian-Early Devonian of China and Vietnam (Yu, 1998; Zhu and Schultze, 1997; Zhu et al., 1999) have resulted in several opposing hypotheses of osteichthyan in terrelationships. However, the absence of data on the poorly known onychodontiform group has meant that key information relevant to the debate has not been previously available. In this paper some aspects of the anatomy of the new Gogo Onychodus, are compared with recently described material of Psarolepis, the oldest known possible sarcopter ygian fish, which have immediate bearing on competing schemes of basal osteichthyan phylogeny. It must be pointed out that a complete description of the new Gogo Onychodus material is currently being prepared by the author, Dr. Per Ahlberg, Prof. Ken Campbell, and Dr. Dick Barwick in association with the notes and descriptions from the late Dr. S. M. Andrews, so the views presented here are the sole opin ions of the author.

Moythomasia is one of the most speciose and completely known of all Devonian actinopterygian genera and has been incorporated into numerous phylogenetic studies. However, several species remain incompletely documented despite being known from excellent fossil material. Specimens from the Late Devonian of Germany and Australia are described herein. A form from Bergisch Gladbach, Germany, previously described by Jessen as Moythomasia cf. striata, is recognized as a new species: M. lineata, sp. nov. Newly prepared specimens of Moythomasia durgaringa from the Gogo Formation, Western Australia, allow for the first rigorous full-body reconstructions of this species. Aspects of the dermal skeleton and body shape of this form are updated over previous descriptions. The genus is currently problematic owing to the highly fragmentary nature of the type species, M. perforata from Kokenhusen; however, it is considered provisionally valid owing to distinctive cranial ornamentation. The three completely known sp...