A Paper Nautilus (Octopoda, Argonauta) From the Miocene Pakhna Formation of Cyprus

Martill, David M.; Barker, Michael J.

doi:10.1111/j.1475-4983.2006.00578.x

Cited by 9 publications

(10 citation statements)

References 7 publications

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“…Variation in shell characters is continuing to be used to designate new fossil argonaut species (Stadum and Saul, 2000), and many have been erected based on single fossilised shells (e.g. Martill and Barker, 2006). Saul and Stadum (2005) reviewed the current situation stating: "ten fossil argonaut species have been placed into four genera based on the absence or presence of keels and the degree of sculpture" (p. 520).…”

Section: Discussionmentioning

confidence: 99%

Recognising variability in the shells of argonauts (Cephalopoda: Argonautidae): the key to resolving the taxonomy of the family

Finn¹,

Victoria²

2018

Mem. Mus. Vic.

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Finn, J.K. 2018. Recognising variability in the shells of argonauts (Cephalopoda: Argonautidae): the key to resolving the taxonomy of the family. Memoirs of Museum Victoria 77: 63-104. Argonauts (Cephalopoda: Argonautidae) are a family of pelagic octopuses that are most commonly recognised by the beautiful white shells of females (known as paper nautiluses), prized by beachcombers the world over. Taxonomic delineation of the group has historically relied exclusively on features of the shells of females and has resulted in more than 50 species names being coined worldwide. This approach has created considerable confusion in the taxonomy of the family because argonaut shells are not true molluscan shells and display considerable variation in form. This study closely examined a large number of argonaut shells from museum collections throughout the world. Two types of shell formation that had been previously attributed to separate argonaut species were recognised within individual shells. It is proposed here that the different shell forms reflect the effects of ecological or biological factors or events, often manifesting as dramatic changes in shell growth and shape within the development of an individual shell. The resulting combinations of shell formation types clearly explain both the extreme variation observed across large numbers of argonaut shells and the high number of nominal species names coined in the past. Researchers coining new fossil argonaut species based solely on shell characters are advised to proceed with caution. This study supports parallel morphological and molecular research recognising the existence of only four extant argonaut species worldwide: Argonauta argo, A. hians, A. nodosus and A. nouryi.

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Section: Discussionmentioning

confidence: 99%

Recognising variability in the shells of argonauts (Cephalopoda: Argonautidae): the key to resolving the taxonomy of the family

Finn¹,

Victoria²

2018

Mem. Mus. Vic.

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“…8) Fossil argonaut egg-cases are extremely rare (Martill and Barker, 2006 (Bandel and Dullo, 1984;Saul and Stadum, 2005).…”

Section: Accepted Manuscriptmentioning

confidence: 98%

The Canary record of the evolution of the North Atlantic Pliocene: New 40Ar/39Ar ages and some notable palaeontological evidence

Meco

Koppers

Miggins

et al. 2015

Palaeogeography, Palaeoclimatology, Palaeoecology

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Two new 40 Ar/ 39 Ar ages (*) and previously published K/Ar ages of basaltic pillow lava flows are coeval with closely-related fossiliferous marine layers, allowing us to establish the beginning (5.8; 5.0; 4.8 Ma at Ajuí, Fuerteventura Island and 4.8 ± 0.03 Ma (2)* at Tamaraceite) and a middle stage (4.20 ± 0.18 Ma (2)* at La Esfinge in Gran Canaria Island) of Early Pliocene marine deposits in the Canary A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 Islands. Here the presence of tropicopolitan fossils (Megaselachus megalodon, Janthina typica) suggest the influence of a possible Central American Circumtropical Current during the Pliocene and in the North Atlantic basin. The presence of both Janthina typica and the Argonauta argo also indicate the occurrence of tropical storms in the area of the Canary Islands around that time. In addition, the pillow lava flow at La Esfinge overlies a submarine pyroclastic layer containing Ostrea offreti that was preserved in its life position, a fossil from the terminal Miocene and commonly found on the south eastern Iberian Peninsula. At La Cruz on Fuerteventura Island, a dune formed above marine deposits lies beneath a palaeosol and a basaltic lava flow that is was K/Ar dated at 2.9 Ma. Near El Mármol in Gran Canaria the corresponding palaeosol lies between lava flows K/Ar dated at 3 Ma. Based on these observations, we argue in this paper that the first appearance of the Canary Current, the eastern boundary current of the North Atlantic sub-tropical gyre, occurred between 4.2Ma and 2.9 Ma ago. This was followed by a major sea level drop (of about 40 m) and the formation of a first fossil-bearing palaeosol which indicate that major climate change that took place around 2.95-2.82 Ma.

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“…The now‐extinct S. albyi dominates Pliocene (3–9 Ma) fossil deposits in southern Spain, Tunisia, Italy, Crete and Cyprus (Gaudant 2002; Gaudant et al. 2005; Martill & Barker 2006) and, while it persisted through the Messinian Salinity Crisis (5.5–6 Ma), this species disappeared from the Mediterranean fossil record during the early Pleistocene (approximately 3 Ma), when it was replaced by the modern S. acus (Landini & Sorbini 2005). More recent (1–3 Ma) fossil deposits in the Adriatic and central Mediterranean are dominated by this species (Landini & Sorbini 2005), and S. acus remains one of the most widespread European Syngnathus species (Dawson 1986).…”

Section: Introductionmentioning

confidence: 99%

The impact of Pleistocene glaciation across the range of a widespread European coastal species

Wilson

Veraguth

2010

Molecular Ecology

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There is a growing consensus that much of the contemporary phylogeography of northern hemisphere coastal taxa reflects the impact of Pleistocene glaciation, when glaciers covered much of the coastline at higher latitudes and sea levels dropped by as much as 150 m. The genetic signature of postglacial recolonization has been detected in many marine species, but the effects of coastal glaciation are not ubiquitous, leading to suggestions that species may intrinsically differ in their ability to respond to the environmental change associated with glacial cycles. Such variation may indeed have a biological basis, but apparent differences in population structure among taxa may also stem from our heavy reliance on individual mitochondrial loci, which are strongly influenced by stochasticity during coalescence. We investigated the contemporary population genetics of Syngnathus typhle, one of the most widespread European coastal fish species, using a multilocus data set to investigate the influence of Pleistocene glaciation and reduced sea levels on its phylogeography. A strong signal of postglacial recolonization was detected at both the northern and eastern ends of the species' distribution, while southern populations appear to have been relatively unaffected by the last glacial cycle. Patterns of population variation and differentiation at nuclear and mitochondrial loci differ significantly, but simulations indicate that these differences can be explained by the stochastic nature of the coalescent process. These results demonstrate the strength of a multilocus approach to phylogeography and suggest that an overdependence on mitochondrial loci may provide a misleading picture of population-level processes.

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A Paper Nautilus (Octopoda, Argonauta) From the Miocene Pakhna Formation of Cyprus

Cited by 9 publications

References 7 publications

Recognising variability in the shells of argonauts (Cephalopoda: Argonautidae): the key to resolving the taxonomy of the family

Recognising variability in the shells of argonauts (Cephalopoda: Argonautidae): the key to resolving the taxonomy of the family

The Canary record of the evolution of the North Atlantic Pliocene: New 40Ar/39Ar ages and some notable palaeontological evidence

The impact of Pleistocene glaciation across the range of a widespread European coastal species

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