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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

New Devonian fossil material from Bolivia includes internal molds of two species of paleotaxodont bivalve, Palaeoneilo musculosa (Knod) and P. pondeana (Hartt and Rathbun), with numerous accessory muscle scars. The unusual pattern of these scars appears to have been derived from excessive splitting. These muscle scars are described and a tentative interpretation is made. An adaptative role cannot be determined with certainty and it appears that these patterns were short-lived novelties without later success.

Reconsideration of the Devonian marine lithological succession in the Gamoneda section of southernmost Bolivia evidences that the distinction of the Gamoneda Formation is not justified. Corresponding deposits have to be assigned to the Icla Formation of the central Subandean Zone. Indeed, in the Gamoneda area the local Devonian sequence only differs from that of the typical lcla and Presto areas in the better development of sandy levels. The occurrence of the Lower Devonian Scaphiocoelia boliviensis Zone in the lowermost beds of the section, just above the Santa Rosa Formation, is established for the first time. An eodevonariid chonetoidean brachiopod (Lomaella sp. cf. L. primoris) is recorded for the first time from Bolivia, and a new fissiculate blastoid is described: Brachyschisma ? gamonedensis. The whole fauna allows to establish correlations both with the central Subandean Zone and with the Argentine Precordillera. Discovery of extra Malvinokaffric fauna) elements raises again the palaeobiogeographical relationships between these areas.

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