Early Silurian trilobites from the Broken River area, north Queensland

Abstract

Holloway, D. J., 1 994. Early Silurian trilobites from the Broken River area, north Queensland. Memoirs of the Museum of Victoria 54: 243-269. A Late Llandovery (Telychian) trilobite fauna is described from the Poley Cow Formation in the Broken River Province of north Queensland. Taxa recorded are Kosovopeltis, Proetus (s.l), WarburgeUdl, Otarion, Mauwtarion, Seharvia, Youngia, Sphaerexochus, Sphaerocoryphe, Coronocephalus? aff. urbis Strusz, 1980. Ceratocephala, the new encrinurid genus Prpstrix, and the new species Prostrix amnicola, Batocarafritillum, Gravicalymenel vaccina and Gaotania bimusa. Youtlgia and Gaotania are recorded from Australia for the first time. Batocara Strusz, 1 980 is considered to be a senior subjective synonym of Pacifieurus Ramskold, 1986a.

Trilobite faunas and palaeoenvironmental setting of the Silurian (early Ludlow) Melbourne Formation, central Victoria

“…Few flexicalymenines have been described from the Silurian of eastern Australia. As noted by Holloway (1994), kilmorensis closely resembles S. vaccina (Holloway) from the Llandovery of north Queensland: kilmorensis differs in having larger L1 and L2, wider glabella at L2, a weak hypostomal middle furrow, a wide, and rounded (rather than triangular) medial notch on the hypostomal posterior margin, and deeper pygidial pleural and interpleural furrows which reach the border. S. kilmorensis is quite distinct from S. coppinsensis (Chatterton & Campbell) from the Wenlock of the A.C.T.…”

“…on the border), and the "straighter course" of the posterior branch of the facial suture. As suggested by Holloway & Neil (1982) and Holloway (1994), these differences can be attributed to tectonic distortion. Ross (1967) noted that glabellar length-width ratios are surprisingly uniform at a 1:1 ratio in the family, and that deviations from the norm are indicative of degree of deformation.…”

“…(1980) noted that the genera are difficult to distinguish, the eye position, eye shape, width of the cranidial anterior border and shape of the pygidium being the most important diagnostic characters, and on these characters simpliciculus shows some resemblance to Encrinuroides. However Strusz (1980), Edgecombe & Chatterton (1992) and Holloway (1994) noted that many of the diagnostic features of Encrinuroides are primitive amongst encrinurids and occur in several encrinurid genera, including Cromus. Edgecombe & Chatterton (1990) restricted Encrinuroides to a monophyletic group of Ordovician species.…”

“…Price (1982) argued that the wide range in preglabellar morphology within a lineage of flexicalymenine species (Calymene quadrata King, Gravicalymene pontilis Price, G. arcuata Price) from the late Ordovician of Wales supported the synonymy of Sthenarocalymene and Gravicalymene. Following Price's argument, Holloway (1994) expressed uncertainty on the relationships between species of Gravicalymene and Sthenarocalymene and tentatively assigned species typical of the latter to Gravicalymene.…”

The paleobiogeographical significance of the Silurian and Devonian trilobites of Japan

“…Of the taxa belonging to those families dealt with in this paper, Bumastella, Rhaxeros and Lalax are assigned to the Illaenidae and Japonoscutellum , Illaenoscutellum , Kosovopeltis and Borenoria to the Scutelluidae, following Holloway and Lane (, , ). Revision of Encrinuridae by Holloway (), Ramsköld (), Strusz (), and Zhang () suggests links between Australia, Japan, and South China. Additionally, revision of the Phacopidae by Kaneko (, ), Stocker et al (), and Zhou and Campbell () has demonstrated links between the KT and SKT as well as with the North China paleocontinent.…”