A Late Permian fossil horseshoe crab (Paleolimulus: Xiphosura) from Poatina, Great Western Tiers, Tasmania

Abstract

The xiphosuran Paleolimulus Dunbar, 1923 is recorded from the Late Permian (Chhidruan) Jackey Shale at Poatina, 41 °4 8'05"S 146°53'06"E. This is the first record of the genus in both Tasmania and the Southern Hemisphere, and extends its distribution to rocks deposited in a high latitude, cold-water environment.

An earliest Triassic age forTasmaniolimulusand comments on synchrotron tomography of Gondwanan horseshoe crabs

“…This formation is largely composed of cross-bedded quartz and feldspathic sandstones, laminated dark grey shales and thin coal lenses ( Pike, 1973 ). Stratigraphically, the fossil was located near the very top of the formation, ∼3 m below the base of the overlying Ross Formation, exposed alongside a cliff on the Poatina Highway (41°48′05″S, 146°53′06″E; Ewington, Clarke & Banks, 1989 ; Bicknell, 2019 ). Based on the lithology, the unit likely represents deposition of lake and river sediments in a non-marine swamp with limited coastal influence ( Banks, 1973 ; Ewington, Clarke & Banks, 1989 ).…”

“…Stratigraphically, the fossil was located near the very top of the formation, ∼3 m below the base of the overlying Ross Formation, exposed alongside a cliff on the Poatina Highway (41°48′05″S, 146°53′06″E; Ewington, Clarke & Banks, 1989 ; Bicknell, 2019 ). Based on the lithology, the unit likely represents deposition of lake and river sediments in a non-marine swamp with limited coastal influence ( Banks, 1973 ; Ewington, Clarke & Banks, 1989 ). While the Jackey Shale at the stratigraphic level of the collection locality lacks age-diagnostic fossils, palynomorphs from other, temporally contiguous sites can be assigned to the Protohaploxypinus microcorpus Zone, equivalent to upper APP6 (see Price, 1997 ) and restricted to the Griesbachian substage, early Induan (Early Triassic) based on previous studies in the Sydney Basin ( Laurie et al, 2016 ; Mays et al, 2020 ).…”

“…The presence of abundant latest Permian macroflora at stratigraphic levels below the level of T . patersoni in the Jackey Shale does suggest that, at least at some locations, the formation does extend into the latest Permian ( Ewington, Clarke & Banks, 1989 ). Nonetheless, given the high stratigraphic position of T .…”

New austrolimulid from Russia supports role of Early Triassic horseshoe crabs as opportunistic taxa

“…Franconiolimulus pochankei , the youngest austrolimulid, has a cardiac ridge, distally effaced occipital bands, and a thoracetronic free lobe, none of which are observed in the Petropavlovka Formation material. Tasmaniolimulus patersoni has pronounced thoracetronic free lobes, as well as keeled cardiac and medial thoracetronic lobes ( Ewington, Clarke & Banks, 1989 ; Bicknell, 2019 ). These are not observed in the Petropavlovka Formation material, excluding the new fossils from this Lopingian (259.1–251.9 Ma) genus.…”

Panduralimulus Babcocki N. Gen. And Sp., a New Limulacean Horseshoe Crab From the Permian of Texas

“…To the list of taxa previously as signed to the Paleolimulidae and now placed in other families should be added a reference to Paleolimulus sp. from Upper Permian rocks of Tasmania (Ewington et al, 1989). Although the specimen bears some resemblance to Paleolimulus, the identity has yet to be confirmed.…”