A middle Eocene basking shark (Lamniformes, Cetorhinidae) from Antarctica.

Cione, Alberto Luis; Reguero, Marcelo Alfredo

doi:10.1017/s095410209800011x

Cited by 40 publications

(23 citation statements)

References 8 publications

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“…Although the extant fauna of Antarctica is sparse, chondrichthyans are much better represented in the fossil record (Grande & Eastman, 1986; Long, 1992; Cione & Reguero, 1998; Kriwet, 2005) than in Australia. Australia and South America parted from the Antarctic landmass by the late Eocene and, once isolated, a circum‐Antarctic current was established following decoupling of the subtropical gyres (Grande & Eastman, 1986).…”

Section: Discussionmentioning

confidence: 99%

Biogeographic patterns in the Australian chondrichthyan fauna

White

2011

Journal of Fish Biology

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The major biogeographic structure and affinities of the Australian chondrichthyan fauna were investigated at both interregional and intraregional scales and comparisons made with adjacent bioregions. Faunal lists were compiled from six geographical regions with species from these regions assigned to distributional classes and broad habitat categories. Australian species were further classified on provincial and bathomic structure following bioregionalization outputs from regional marine planning. About 40% of the world's chondrichthyan fauna occurs in Indo-Australasia (482 species) of which 323 species are found in Australian seas. The tropical Australian component, of which c. 46% of taxa are regional endemics, is most similar to faunas of Indonesia, New Guinea and New Caledonia. The temperate Australian component is most similar to New Zealand and Antarctica with about half of its species endemic. Highest levels of Australian endemism exist in bathomes of the outer continental shelf and upper slope. A relatively high proportion of regional endemism (57% of species) on the slope in the poorly surveyed but species-rich Solanderian unit is probably due to high levels of large-scale habitat complexity in the Coral Sea. The richness of demersal assemblages on the continental shelf and slope appears to be largely related to the spatial complexity of the region and the level of exploration. Much lower diversity off Antarctica is consistent with the pattern in teleosts. The complex chondrichthyan fauna of Australia is confirmed as being amongst the richest of the mega-diverse Indo-West Pacific Ocean. Species-level compositions of regional faunas across Indo-Australasia differ markedly because of moderate to high levels of intraregional speciation. Faunal assemblages in Australian marine provinces and bathomes differ from each other, supporting a broader pattern for fishes that underpins a marine planning framework for the region.

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Section: Discussionmentioning

confidence: 99%

Biogeographic patterns in the Australian chondrichthyan fauna

White

2011

Journal of Fish Biology

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“…Suspension feeding in the cartilaginous (elasmobranch) fishes evolved approximately 66–22 million years ago (Cione and Reguero, ; Friedman et al, ) and includes four independently evolved lineages of fishes (Cetorhinidae, Megachasmidae, Rhincodontidae, and Mobulidae) (Sanderson and Wassersug, ). Filtration is accomplished by the gill rakers and elasmobranch gill rakers are different than those of bony fishes which are typically long, thin projections from the branchial arch.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the Structure and Composition of the Branchial Filters in Suspension Feeding Elasmobranchs

Paig-Tran

Summers

2014

The Anatomical Record

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The four, evolutionarily independent, lineages of suspension feeding elasmobranchs have two types of branchial filters. The first is a robust, flattened filter pad akin to a colander (e.g., whale sharks, mantas and devil rays) while the second more closely resembles the comb-like gill raker structure found in bony fishes (e.g., basking and megamouth sharks). The structure and the presence of mucus on the filter elements will determine the mechanical function of the filter and subsequent particle transport. Using histology and scanning electron microscopy, we investigated the anatomy of the branchial filters in 12 of the 14 species of Chondrichthyian filter-feeding fishes. We hypothesized that mucus producing cells would be abundant along the filter epithelium and perform as a sticky mechanism to retain and transport particles; however, we found that only three species had mucus producing goblet cells. Two of these (Mobula kuhlii and Mobula tarapacana) also had branchial cilia, indicating sticky retention and transport. The remaining filter-feeding elasmobranchs did not have a sticky surface along the filter for particles to collect and instead must employ alternative mechanisms of filtration (e.g., direct sieving, inertial impaction or cross-flow). With the exception of basking sharks, the branchial filter is composed of a hyaline cartilage skeleton surrounded by a layer of highly organized connective tissue that may function as a support. Megamouth sharks and most of the mobulid rays have denticles along the surface of the filter, presumably to protect against damage from large particle impactions. Basking sharks have branchial filters that lack a cartilaginous core; instead they are composed entirely of smooth keratin.

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“…For example, high latitude climates remained warm and equable relative to the present (cf. Greenwood and Wing 1995, Jordan 1996, Wing and Greenwood 1996 and the fossil remains of a basking shark, now unknown in Subantarctic or Antarctic waters, occurs in Middle Eocene sediments on Seymour Island on the Antarctic Peninsula (Cione and Reguero 1998). Summer SSTs during the early Middle Eocene were similar to the present-day United States Gulf Coast whilst winters were 7-8 0 C warmer due to strong oceanic heat transport (Andreasson and Schmitz 2000).…”

Section: Mid Eocene Climatic Transition [~48 Ma]mentioning

confidence: 99%

Fossil leaves of Banksia, Banksieae and pretenders: resolving the fossil genus Banksieaephyllum

Carpenter

Jordan

Hill

2016

Aust. Systematic Bot.

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The genus Banksieaephyllum, originally erected for cuticle-bearing fossil leaves of subtribe Banksiinae (Proteaceae subfamily Grevilleoideae, tribe Banksieae), is reassessed. Of the 18 described species, nine are accepted within Banksia, including Banksieaephyllum obovatum Cookson & Duigan, which is synonymised with B. laeve Cookson & Duigan on the basis of new cuticular preparations. Two other species are transferred to Banksieaefolia gen. nov., a genus erected for Banksieae of uncertain affinities, and which presently includes only fossils that probably belong to subtribe Musgraveinae. The seven other Banksieaephyllum species lack definitive characters of Proteaceae (i.e. brachyparacytic stomata and annular trichome bases) and do not have Banksieae-type cylindrical trichome bases. These species are, therefore, not accepted as Proteaceae and are transferred to Pseudobanksia gen. nov., together with another fossil Banksia-like leaf species, Phyllites yallournensis Cookson & Duigan. Lectotypes are chosen for Banksia fastigata H.Deane, Banksieaephyllum acuminatum Cookson & Duigan, Banksieaephyllum angustum Cookson & Duigan and Banksieaephyllum laeve Cookson & Duigan. Implications arising from the re-assessment of Banksieaephyllum include clarification of biome conservatism in Banksieae; Banksia has long had an association with relatively open, sclerophyllous vegetation, and Musgraveinae with rainforest. Pseudobanksia and Banksia share convergent traits, but in contrast to Banksia, Pseudobanksia failed to survive the drying climates and increased fire-frequencies of the Neogene.

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A middle Eocene basking shark (Lamniformes, Cetorhinidae) from Antarctica.

Cited by 40 publications

References 8 publications

Biogeographic patterns in the Australian chondrichthyan fauna

Biogeographic patterns in the Australian chondrichthyan fauna

Comparison of the Structure and Composition of the Branchial Filters in Suspension Feeding Elasmobranchs

Fossil leaves of Banksia, Banksieae and pretenders: resolving the fossil genus Banksieaephyllum

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