Abstract

A monotypic genus of a new family of Merostomoidea is described from the Middle Triassic of Brookvale, New South Wales, Australia. The known range of the subclass, previously recorded from the Middle Cambrian, is extended considerably by this record.

Three well preserved non-insect arthropod specimens, apart from the xiphosuron, Austrolimulus ftetcheri Riek, (1955), have been collected from the Middle Triassic freshwater sediments at Brookvale, New South Wales. These sediments also contain abundant insects and fish. These three specimens bear a considerable resemblance in body shape to both the Synziphosurina (Merostomata) and the Merostomoidea (Trilobitomorpha). The post-cephalic portion of the body is divided into two distinct regions and ends in a long caudal style. Although appendages are not clearly preserved, their general structure can be distinguished below the crumpled pleural regions in one of the specimens and their bases distinguished in another. These numerous pairs of similar appendages are of trilobitomorph form.

Trilobitomorpha, which are first recorded from the Lower Cambrian, are not known from strata younger than the Middle Permian and almost all the species occurring since the Cambrian are referred to the well-known trilobites (Class Trilobita). The Class Trilobitoidea is, however, recorded from the Devonian as well as from the Cambrian. If these Middle Triassic specimens do belong to the Trilobitoidea they extend the known range of the class very considerably. There seems little doubt from a study of the insect remains that the sediments in which these specimens occur are of Triassic, very probably Middle Triassic, age. Etc.

 
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Bibliographic Data

Short Form
Riek, 1965, Rec. Aust. Mus. 26(13): 327–332
Author
E. F. Riek
Year
1965
Title
Merostomoidea (Arthropoda, Trilobitomorpha) from the Australian Middle Triassic
Serial Title
Records of the Australian Museum
Volume
26
Issue
13
Start Page
327
End Page
332
DOI
10.3853/j.0067-1975.26.1965.681
Language
English
Plates
plate 35
Date Published
06 January 1965
Cover Date
30 December 1964
ISSN
0067-1975
CODEN
RAUMAJ
Publisher
The Australian Museum
Place Published
Sydney, Australia
Digitized
07 April 2009
Available Online
23 July 2009
Reference Number
681
EndNote
/Uploads/Journals/17436/681.enw
Title Page
/Uploads/Journals/17436/681.pdf
File size: 222kB
Complete Work
/Uploads/Journals/17436/681_complete.pdf
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