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Early Pliocene tracer of North Atlantic and South Pacific sea surface currents: Janthina typica (Bronn, 1860) (Mollusca: Gastropoda)


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Janthina typica is an extinct, rare, floating species of gastropod from the early Pliocene whose fossils have an unusual geographic distribution, appearing in the eastern North Atlantic archipelagos (Canary, Azores, Madeira and Selvagen Islands), Morocco, and Pacific (New Zealand, Australia and Japan). This study examines the origin of this biogeography and how the species may have dispersed via sea surface currents. We have considered the published ecological aspects of the genus Janthina, the Janthina typica fossil localities, and ocean palaeocurrents. Abundant specimens of J. typica are found in marine deposits on Gran Canaria island (northeast Atlantic), 40Ar/39Ar dated at 4.2 Ma. These deposits therefore accumulated just before the end of the early Pliocene warm climate and closely predate the start of global changes that gave rise to the world’s present climate. In the early Pliocene, the cold Canary Current did not yet exist. The subtropical northeastern Atlantic Ocean was warmer than today and its waters would have met the Circumtropical Current that crossed the Central American Seaway from the Caribbean to the Pacific. From there, the South Equatorial Current flowed towards the eastern coast of Indonesia before splitting north towards Japan and south as the East Australian Current. The latter must also have extended along the southern coast of Australia, crossing the Bass Strait before reaching the area of modern-day Perth in southwestern Australia. The reverse journey (from Australia to the eastern Atlantic Ocean) would have posed far more obstacles, and is considered improbable. J. typica therefore likely originated in the East Atlantic. The main causes for its extraordinary geographic distribution are its ecology as a floating animal in warm water, tectonic plate movements that permitted an open Central American Seaway and a restricted Indonesian Seaway, and Earth’s rotation and its influence on marine currents.
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Meco et al.
RMCG | v. 33 | núm. 2 |
Meco, J., Lomoschitz A, Betancort, J.-F., 2016, Early Pliocene tracer of North Atlantic and South Pacific sea surface currents: Janthina typica (Bronn, 1860) (Mollusca:
Gastropoda): Revista Mexicana de Ciencias Geológicas, v. 33, núm. 2, p. 192-197.
Janthina typica is an extinct, rare, floating species of gastropod
from the early Pliocene whose fossils have an unusual geographic
distribution, appearing in the eastern North Atlantic archipelagos
(Canary, Azores, Madeira and Selvagen Islands), Morocco, and Pacific
(New Zealand, Australia and Japan). This study examines the origin
of this biogeography and how the species may have dispersed via sea
surface currents. We have considered the published ecological aspects
of the genus Janthina, the Janthina typica fossil localities, and ocean
palaeocurrents. Abundant specimens of J. typica are found in marine
deposits on Gran Canaria island (northeast Atlantic), 40Ar/39Ar dated
at 4.2 Ma. These deposits therefore accumulated just before the end
of the early Pliocene warm climate and closely predate the start of
global changes that gave rise to the world’s present climate. In the early
Pliocene, the cold Canary Current did not yet exist. The subtropical
northeastern Atlantic Ocean was warmer than today and its waters
would have met the Circumtropical Current that crossed the Central
American Seaway from the Caribbean to the Pacific. From there, the
South Equatorial Current flowed towards the eastern coast of Indonesia
before splitting north towards Japan and south as the East Australian
Current. The latter must also have extended along the southern
coast of Australia, crossing the Bass Strait before reaching the area
of modern-day Perth in southwestern Australia. The reverse journey
(from Australia to the eastern Atlantic Ocean) would have posed far
more obstacles, and is considered improbable. J. typica therefore likely
originated in the East Atlantic. The main causes for its extraordinary
geographic distribution are its ecology as a floating animal in warm
water, tectonic plate movements that permitted an open Central
American Seaway and a restricted Indonesian Seaway, and Earth’s
rotation and its influence on marine currents.
Key words: pelagic mollusk; warm water species; Pliocene climate;
plate tectonics; Coriolis effect; early Pliocene currents.
Janthina typica es un molusco gasterópodo flotante, extinguido
y raro del Plioceno. Sus fósiles presentan una distribución geográfica
inusual apareciendo en los archipiélagos del este del Atlántico norte
(Islas Canarias, Azores, Madeira y Salvajes), en Marruecos y en el
oeste del Pacífico (Nueva Zelanda, Australia y Japón). En el presente
trabajo se estudia la causa de esta biogeografía y de su dispersión
mediante corrientes marinas de superficie. Para ello se han considerado
los aspectos ecológicos del género Janthina, las localidades fósiles de J.
typica y las paleocorrientes oceánicas. Abundantes ejemplares de J. typica
se han encontrado en depósitos marinos de la Isla de Gran Canaria
que han sido datados en 4.2 Ma. Esta época es justamente anterior a
la terminación del clima cálido del Plioceno inferior y se aproxima al
comienzo de los cambios globales que van a dar lugar al modelo climático
actual. En el Plioceno inferior la corriente fría de Canarias no existía.
El Atlántico norte subtropical era más cálido que en la actualidad y sus
aguas se encontrarían con la Corriente Circumtropical que cruzaba
el Paso de América Central desde el Mar Caribe al Océano Pacífico.
Desde ahí, la Corriente Ecuatorial del Sur fluye hacia las costas de
Indonesia en donde se divide, al norte hacia Japón y al sur hacia las
costas de Australia llegando a alcanzar una posición frente a la actual
ciudad de Perth tras atravesar el Estrecho de Bass. El trayecto inverso
(de Australia al este del océano Atlántico) encontraría más obstáculos
y puede considerarse altamente improbable. De ello se deduce que J.
typica se originó en el Atlántico europeo. Las principales causas de su
extraordinaria distribución geográfica son su ecología, por ser un animal
flotante en aguas cálidas, los movimientos de las placas tectónicas, que
permitieron el paso de América Central y un estrechamiento del paso
de Indonesia, y el movimiento de rotación de la Tierra y su influencia
sobre las corrientes marinas.
Palabras clave: moluscos pelágicos; fauna de aguas cálidas; clima del Plio-
ceno; placas tectónicas; efecto Coriolis; corrientes del Plioceno temprano.
On Gran Canaria (Canary Islands, Spain; Figure 1) marine de-
posits at La Esfinge site (Figure 2) host a considerable accumulation
of Janthina typica (Figure 3). These deposits have been recently dated
(Meco et al., 2015) using 40Ar/39Ar to 4.2 Ma from samples of pillow
lava that entered into contact with it. The aim of the present paper is to
show the geographic distribution of J. typica in the Atlantic and Pacific
oceans during the early Pliocene. The paper presents hypotheses that
could explain its notable dispersal as a floating animal in warm water.
v. 33, núm. 2, 2016, p. 192-197
Early Pliocene tracer of North Atlantic and South Pacic sea surface currents:
Janthina typica (Bronn, 1860) (Mollusca: Gastropoda)
Joaquín Meco1,*, Alejandro Lomoschitz2 and Juan-Francisco Betancort1
1 Departamento de Biología, Universidad de Las Palmas de Gran Canaria (ULPGC),
35017, Las Palmas de Gran Canaria, Canary Islands, Spain.
2 Instituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria (ULPGC),
35017 Las Palmas de Gran Canaria, Canary Islands, Spain.
Early Pliocene tracer of North Atlantic and South Pacific sea surface currents
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18º 17º 16º 15º 14º W
El Hierro
La Palma
Gran Canaria
02 3 4
15 km
La Esfinge
Gran Canaria
Las Palmas de
Gran Canaria
Janthina typica: ecology and palaeodistribution
The geographic distribution of fossil specimens of the tropical
gastropod Janthina typica (Bronn, 1860) (= Hartungia typica Bronn
= Janthina Hartungi Mayer = Hartungia chuberti Chavan) is strik-
ing for the great distances between the sites where this taxon has
been found: from the Canary Islands (Meco et al., 2015), the Azores
(Bronn, 1860; Mayer, 1864), Madeira (Mayer, 1864), S elvagem Grande
(Joksimowitsch, 1911) and Atlantic Morocco (Chavan, 1951) to the
antipodean locations of New Zealand, Australia and Japan (Tomida
and Kitao, 2002; Beu and Raine, 2009).
The current Janthinidae comprise a family of pelagic gastro-
pods that live in colonies in warm and temperate seas, floating on a
bubble-like raft of their own making, bound by mucus secreted from
the organisms´ feet, and they feed on hydrozoans such as Velella and
Physalia (Nicklès, 1950; Laursen, 1953; Powell, 1979; Janssen, 2007;
Churchill et al., 2011). This unusual adaptation enables them to travel
enormous distances by drifting along with the currents, and s ometimes
they are cast onto beaches in significant numbers by on-shore winds
(Beu and Raine, 2009).
J. typica is a fossil species from the early Pliocene (5.3 Ma to
3.6 Ma; Gradstein et al., 2004). The other localities where J. typica
is found span much of the Pliocene. On Santa María Island in the
Azores, specimens have been found in Feteirinhas and Pinheiro on
the southeastern tip of the island (Reiss and Bronn, 1863). In a nearby
locality, Pedra que Pica, the marine deposits have been attributed to
the Messinian based on an 87Sr/86Sr age of 5.51 Ma (Kirby et al., 2007).
The oldest shield of Madeira Island has yielded a 40Ar/39Ar age >4.6 Ma
(Geldmacher et al., 2000) to 5.3 Ma (Klügel, 2009); therefore, the marine
deposits at the Sao Vicente locality are also probably early Pliocene.
In Selvagem Grande the marine deposits accumulated before the
Pliocene volcanic cycle occurring at 3.4 Ma (Geldmacher et al., 2001).
The marine deposits at Aïn Sebaa near Casablanca in Morocco are
referred to the Piacenzian stage (Chavan, 1951). In New Zealand, J.
typica has been found in deposits assigned to the Kapitean to Waipipian
stages (Beu and Raine, 2009), which are roughly contemporaneous with
the uppermost Messinian-Lower Zanclian to Lower Piacenzian stages
(ca. 6 Ma to ca. 3 Ma). In southeastern Australia (Victoria) and western
Australia (Perth) the deposits that yielded J. ty pica were included in the
Kalimnan stage (Tate, 1893; Beu and Raine, 2009), which corresponds
roughly to the Upper Zanclian and Lower Piacenzian (ca. 4.4 to ca.
3 Ma). The J. typica specimens found in Kyushu, South Japan, were
included in the earliest Pliocene (Tsuma Formation ca. 5 Ma) and in the
latest Pliocene (Takanabe Formation, 2.6–2.5 Ma; Tomida et al., 2013).
In the early Pliocene (5 Ma to 4 Ma), Earth's climate was warm
in many regions and temperate in others. The gradual cooling that
followed the early Pliocene led to the establishment of modern tem-
perature patterns (Fedorov et al., 2013). Thus, the age of the Gran
Canaria marine deposits with J. typica (4.2 Ma) falls within the early
Pliocene warm period, but is close to the transition into the cooling
period that followed.
The geological characteristics and sedimentary interpretation of
the Gran Canaria marine deposits that contain a significant acc umula-
tion of J. typica shells, along with their isotopic age (4.2 Ma; Figure 2),
were reported in a previous paper (Meco et al., 2015). Other marine
deposits of Las Palmas de Gran Canaria are also early Pliocene but these
sediments provided a 40Ar/39Ar age of 4.8 Ma (Meco et al., 2015) and
no fossil specimens of J. typica have been found in them. The fossils
contained indicate a coastal and littoral habitat (e.g., Patella ambrog-
gii Lecointre) with a warm intertropical climate (e.g., Persististrombus
coronatus Defrance), Nerita emiliana Mayer).
In the present paper the ecology of Janthina is discussed and the
oceanic currents of ca. 4 Ma are summarized, mainly from the findings
Figure 1. Location of La Esfinge site in northeastern Gran Canaria, where Janthina typica has been found.
Meco et al.
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1 cm
of the Ocean Drilling Program (ODP), which allow sites where fossil
specimens of J. typica have been found to be connected. The dispersal
of this species from the eastern Atlantic to the western Pacific (or
vice-versa), must have been determined by the sea surface currents
at that time, which were in turn controlled by tectonic plate move-
ments, and pressure gradients and the effect of the Earth’s rotation
(the Coriolis effect).
Around 4.2 Ma ago, the geographic distribution of land masses
(and so of the seas) differed significantly from today. Two important
changes took place around this time that were caused by the movement
of tectonic plates, and resulted in the closure of inter-ocean connec-
tions. One change caused the closure of the Central American Seaway,
as the South American, Caribbean and North American plates moved
closer together, and the Atlantic Ocean became isolated from the Pacific
Ocean (Schmidt, 2007). In the other major change, the Indonesian
Seaway closed as the Australian and Eurasian plates moved closer
together, bringing about a partial isolation of the Pacific Ocean from
the Indian Ocean (Gallagher et al., 2009).
Closure of Central American seaway
The closure of the Central American Seaway (also called the
Panamanian Seaway) can be deduced from the progressive differen-
tiation in salinity between the Caribbean Sea and the Pacific Ocean
which was taking place about 4 Ma ago (Keigwin, 1982). This change is
documented in isotopic analyses of foraminifera extracted from ODP
oceanic drilling samples, including ODP Site 1241 (Groeneveld et al.,
2006) in the eastern equatorial Pacific Ocean, and ODP Site 999 (Steph
et al., 2006) in the Caribbean Sea. Salinity was virtually the same on
both sides of present day Panama 4.2 Ma ago (Sarnthein et al., 2009),
but shortly thereafter began the first phase of an increase in Caribbean
salinity that concluded some 3.7 Ma ago. This time interval is consid-
ered to reflect the initial stage in the closure of the Central American
Seaway (Chaisson and Ravelo, 2000). Thus, 4.2 Ma ago, the seaway still
existed, and the Circumtropical Current that flowed east-to-west from
the Caribbean to the Pacific, was still operative (Iturralde-Vinent and
MacPhee, 1999; Mestas-Nuñez, 2014).
The Pacific Ocean warm pool
A comparison of foraminifera from ODP Site 806, near the
Solomon Islands, and ODP Site 847, near the Galapagos Islands,
reveals important changes 4.2 Ma ago that establish the timing of
salinity differentiation at the latitude of Ecuador between the eastern
and western sides of the Pacific Ocean. From this point onwards an
enlargement of the West Pacific Warm Pool began and an eastwards
lengthening of the cold tongue was initiated. The evolution of plank-
Figure 2. Geological context at La Esfinge (Gran Canaria). (a) Section showing
the fossiliferous marine deposit (2) between pillow lavas with a 4.2 Ma 40Ar/39Ar
age (1) (from Meco et al., 2015) and Pleistocene volcanics (3); (b) detail of layer
2: 2a marine sands with fossils inside and 2b aeolian sands; (c) accumulation
of Janthina typica at the top of layer (2).
Figure 3. Janthina typica (Bronn, 1861) showing a) apertural view b) apical view
c) lateral view (LE2051) from the early Pliocene (4.2 Ma) at La Esfinge (Gran
Canaria, Spain). Note that it has faint but visible folds; d) drawing of apertural
view from early Pliocene (Opoitian) at southwest Aukland, New Zealand (Beu
and Maxwell, 1990); e) apertural view (MGF3472) from the Pliocene of Japan
(Tomida et al. 2013); f) apertural view (MFM112203) from Upper Pliocene of
Japan (Tomida and Kitao, 2002) as Hartungia japonica (Tomida and Itoigawa,
Early Pliocene tracer of North Atlantic and South Pacific sea surface currents
RMCG | v. 33 | núm. 2 |
tonic foraminifera and their ecology suggest that surface water cooling
was taking place between 4.5 Ma and 4.0 Ma (Chaisson and Ravelo,
2000, Li et al., 2006), which is interpreted to be a consequence of the
Panamanian Seaway closure.
Indonesian Seaway closure
Foraminiferal analyses of Miocene to Holocene strata of the
northwestern continental shelf off Australia have been used to chart
the influence of the West Pacific Warm Pool (Gallagher et al., 2009).
Between 10 Ma and 4.4 Ma ago, the collision of Australia and Asia nar-
rowed the Indonesian Throughflow. This “S” shaped current connects
the West Pacific Warm Pool and the Indian Ocean, passing from sout h
of the Philippines through the Makassar Strait (between Borneo and
Sulawesi), turning southwards through the Flores Sea and the Timor
Sea, ultimately heading southwest to the Indian Ocean (Figure 4).
Warmer waters became trapped in the Pacific, creating a central West
Pacific Warm Pool marine biogeographic province spanning a zone
from the equator to 26°N (Gallagher et al., 2009).
Between 4.4 Ma and 4 Ma, Indo-Pacific marine taxa migrated
to waters off of northwestern Australia possibly because of a limited
Indonesian Throughflow, and the absence of these taxa after 4 Ma
indicates the possible restriction of this current. The L eeuwin Current,
which flows from south of Java to the south of Australia along its west
coast, did not begin until much later, in the Early Pleistocene (Gallagher
et al., 2009), and so offered no viable route for faunal migration
4.2 Ma ago. At the same time, beginning with the northward displacement
of New Guinea and the emergence of the islands of Indonesia 5 Ma
ago, exchange between the Pacific and Indian Oceans through the
Indonesian Seaway was interrupted between 4 Ma and 3 Ma (Cane and
Molnar, 2001). This had the effect of redirecting oceanic circulation
from the southern Pacific warm waters northward to Japan surrounded
by relatively cold waters of the northern Pacific. The presence of J.
typica at ca. 5 Ma in southern Japan shows that the warm Kuroshio
Currents flowed strongly in the earliest Pliocene (Tomida et al., 2013).
Southern Australia
The Pliocene climatic and environmental evolution of southeastern
Australia (Bass Strait) indicates that relatively stable and warmer marine
conditions than the present day prevailed throughout most of the early
Pliocene (Gallagher et al., 2003). This corresponds to a period of low
marine δ18O values (corresponding to warmer waters and/or lower
ice volume) from 4.2 Ma to 4.0 Ma (Shackleton et al., 1995). This was
also a time of relatively low ice volume in the Antarctic (Bart 2001;
Gallagher et al., 2003).
There are no significant age differences among the sites where
J. typica has been collected in the Pacific and Atlantic. This suggests
that two opposing hypotheses may explain the path of its biogeo-
graphic dispersal: (a) migration from the eastern Atlantic Islands to
the Australian coasts; or (b) migration from the western Australian
coast to the eastern Atlantic islands.
Hypothesis 1: dispersal of J. typica from the eastern Atlantic Islands
to the western Australian coast
At present, the Azores, Madeira, Salvagen and Canary Islands
are situated within the North Atlantic subtropical gyre. Around 4.2
Ma, the waters were warmer and this gyre would have been weaker
(Meco et al., 2015). Nevertheless, the trade winds and associated
currents likely existed, and would have allowed J. typica to disperse
into the Caribbean Sea, and cross the Central American Seaway to
the equatorial Pacific. Once it reached the equatorial Pacific Ocean,
the trade winds of the intertropical zone could have carried J. typica
westward into the southern hemisphere toward Indonesia. Because
the Indonesian Troughflow was closed at the time, once the Equatorial
Current reached the western Pacific, separate currents may have
formed, one moving northward in the direction of Japan, and another
southward to Australia and New Zealand (Figure 4).
Hypothesis 2: dispersal of J. typica from the western Australian coast
to the eastern Atlantic islands
The reverse route, from the western Pacific to the eastern Atlantic,
would have posed significant difficulties. Two possible paths could be
invoked: (1) following the oceanic gyres through the Indian Ocean
into the South Atlantic, and from there into the North Atlantic. This
would have endangered the survival of J. typica, a warm water species,
as it would have required passage through long sections of cold waters
in both the northern and southern hemispheres; or (2) following the
Equatorial Counter Currents eastward across the Pacific, though this
would have meant overcoming the obstacle of the "doldrums", the
area of low pressure around the equator where prevailing winds are
calm. It should be noted that the Pacific Equatorial Countercurrent
originated in the west and advanced eastward as modern climate
conditions began to set in (Li et al., 2006). Some 4.2 Ma ago, however,
the countercurrent was shorter and the oceanic gyres were only in the
formative stage of their modern configurations (Li et al., 2006). The
Pacific currents were no doubt different from those of today and in
some areas may not have even existed. It would have been difficult for
J. typica to migrate from the western Australian coast to the eastern
Atlantic Ocean ca. 4.2 Ma ago.
Other older species of Janthina are very similar morphologically to
the Canary I. J. typica (4.2 Ma), but designated Hartungia instead in the
literature (for a taxonomic study, see Beu and Raine, 2009). Hartungia
elegans occurred along the Pacific coast of southern and central Japan
during the Late Miocene (planktonic foraminiferal Zone N. 17, at ca.
6.8 Ma; see Tomida and Nakamura, 2001) and Hartungia pehuensis
occurs at Taranaki in northwestern New Zealand also during the Late
Miocene (Marwick, 1926). The Late Miocene oceanic circulation pat-
tern (Iturralde-Vinent and MacPhee, 1999, fig. 10; Li et al., 2006, fig.
8) may have set the precedent for the early Pliocene dispersal route of
J. typica from the Atlantic Ocean to the Pacific Ocean.
The principal explanation for the extraordinary geographic disper-
sal of J. typica are a combination of factors of different scale: ecological,
geological and astronomical. Its ecology as a floating animal in warm
waters and capable of long-distance transport in a short period of time
(for a modern analog, see Bryan et al., 2004) and the tectonic plate
configuration that permitted an open Central American Seaway and
also brought about a restricted Indonesian Seaway. The ancestor of J.
typica is unknown. The great similarity between the Pacific and Atlantic
forms (Figure 3) suggests a rapid dispersal rather than a geographic
speciation. Accordingly, this species must have originated in the west-
ern Atlantic during the Late Miocene or earliest Pliocene and experi-
enced a remarkable dispersal, crossing into the Pacific during the early
Pliocene before reaching the vicinity of present-day Perth in Western
Australia, as well as southern Japan. The presence of J. typica in these
diverse localities indicates that warm waters existed throughout the
dispersal route, and that the Canary Current was at that time warmer.
The Circumtropical Current must have extended to the western Pacific,
Meco et al.
RMCG | v. 33 | núm. 2 |
4,000 km
~ 4.2 Ma
Atlantic Ocean
Pacific Ocean
while the cold Humboldt Current in the area of the Galapagos Islands
must have been weak or absent. On reaching Panama, the Equatorial
Countercurrent must have been deflected southward. This would al-
low connection with the Pacific South Equatorial Current, and end in
a bifurcation in Indonesia with one branch heading north (Kuroshio
Current) and the other south (East Australian Current). This latter
current would extend through the Bass Strait and along the southern
coast of Australia as far as modern-day Pert h, which would also require
some distancing of the West Wind Drift.
We are grateful to Daniel R. Muhs (U.S. Geological Survey), Alan
G. Beu (GNS Science, New Zealand) and to Francisco García-Novo
(Universidad de Sevilla, Spain) for comments on a draft of this manu-
script. We also thank the comments from editor Thomas M. Lehman
(Texas Tech University) and the suggestions of Sandra Gordillo and
two anonymous reviewers.
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Figure 4. Biogeography of Janthina typica and reconstruction of the oceanographic dispersal route around 4.2 Ma in accordance with the most likely hypothesis.
Important localities (pink squares) are shown with numbered circles: (1) Santa Maria I. (Azores Islands), (2) Madeira I., (3) Selvagem Grande I., (4) Casablanca
(Morocco), (5) Gran Canaria I. (Canary Islands), (6) Auckland (New Zealand), (7) Victoria (Australia), (8) Perth (Australia) and (9) Kyushu (Japan). ODP Sites
(black circles). Dispersal route of Janthina typica (black arrows) from the East Atlantic Warm Pool (EAWP), through the Warm Canary Current (WCC), the
Circumtropical Current (CC), the Central America Seaway (CAS), and the South Equatorial Current (SEC), and to the Warm East Australian Current (WEAC); or
trough the Western Pacific Warm Pool (WPWP) to the Proto Kuroshio Current (PKC). Indonesian Through Flow (ITF). T: Trade winds (red arrows).
Early Pliocene tracer of North Atlantic and South Pacific sea surface currents
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... Other Atlantic islands: Madeira, Selvagem Grande, Gran Canaria. Janthina typica has been recorded from three other eastern Atlantic islands (Fig. 14): at São Vicente on the main island of Madeira, at La Esfinge on Gran Canaria, Canary Islands, and at Selvagem Grande, a small island between the Canary Islands and Madeira (Krejci-Graf et al., 1958: 336;Meco et al., 2015Meco et al., , 2016. Mayer (1864a, b: 63) rather casually recorded Janthina hartungi from São Vicente, on the north coast of Madeira. ...
... Gran Canaria Island: La Esfinge, a short distance north of Las Palmas de Gran Canaria, east side of La Isleta, NE Gran Canaria, Canary Islands, material reported by Meco et al. (2015Meco et al. ( , 2016 (ULPGC LE20151-LE20156, 6 specimens loaned by Joaquín Meco, ULPGC; Figs 25N, Q-R, T). As noted above, nearby 40 Ar/ 39 Ar dates on an underlying lava flow provide a maximum age for the Janthina specimens of 4.20±0.18 ...
... 41) show specimens that would not be surprising to find among samples collected in New Zealand or southern Australia. The six specimens observed from the material of Meco et al. (2015Meco et al. ( , 2016 from La Esfinge, Gran Canaria Island (Figs 25N, Q-R, T) are rather fragile, but most are well-preserved, with low to moderately high spires and relatively weak sculpture, but are not as weakly sculptured as the holotype of Eunaticina abyssalis (Simone, 2014) and provide a good basis for understanding the variation that might be expected in the Santa Maria Island population. The two smallest specimens from Gran Canaria are internal moulds, lacking shell. ...
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Fossil and living neustonic gastropods referred previously to Janthinidae are revised and included in Epitoniidae. Species recognized in Janthina Röding, 1798 (= Iodes, Iodina and Amethistina Mörch, 1860, Hartungia Bronn, 1861, Heligmope Tate, 1893, Violetta Iredale, 1929, Parajanthina Tomida and Itoigawa, 1982, and Kaneconcha Kaim, Tucholke and Warén, 2012) are J. typica (Bronn), Messinian-early Piacenzian (latest Miocene-early late Pliocene), c. 7-3.0 Ma (New Zealand, southern Australia, Japan, Morocco, dredged off Brazil, Madeira, Gran Canaria I., Selvagem Grande I., and Santa Maria I., Azores); J. krejcii sp. nov., Zanclean (early Pliocene), c. 4.8-4.3 Ma (Santa Maria I.); J. chavani (Ludbrook), late Piacenzian-early Calabrian (latest Pliocene-early Pleistocene), 3.0-c. 1.7 Ma or later (New Zealand, southern Australia, Japan, mid-Atlantic ridge); J. globosa Swainson, living, and two late Pliocene-early Pleistocene records (Jamaica, Philippines); and J. exigua Lamarck, J. janthina (Linnaeus), J. pallida Thompson, and J. umbilicata d'Orbigny, all Holocene only. Janthina evolved from a benthic epitoniid resembling Alora during Messinian (late Miocene) time, and feeds mainly on colonial cnidarians (Physalia, Velella, Porpita). The extinction of Janthina typica and origination of J. chavani at 3.0 Ma (end of the Pliocene climatic optimum) potentially is useful for world Pliocene correlation. The two Recluzia species, R. johnii (Holten) and R. lutea (Bennett), feed on floating Minyadidae anemones. Recluzia has no fossil record and evolved independently during Holocene time from a benthic epitoniid resembling Alexania and Surrepifungium. Adaptation to a neustonic habit evolved twice in Epitoniidae. Twenty-two neotypes and six lectotypes are designated.
... Paleosols sampled for mineralogy and geochemistry are numbered 1-6, from oldest to youngest. Pliocene fossils include Nerita emiliana and Patella ambroggi (found in lowest marine sand, immediately above the Miocene basalt; in marine sand and gravel below paleosol 1; and in marine sand and gravel unit between paleosols 1 and 2; see Meco et al., 2015Meco et al., , 2016. "Ootecas" below paleosols 5 and 6 are trace fossils of the African-derived Moroccan locust Dociostaurus maroccanus (Meco et al., 2011). ...
... The fossil mollusks Patella ambroggii and Nerita emiliana (Figs. 6b, c) are extinct species and are not known to occur in deposits younger than the early Pliocene (Meco and Stearns, 1981;Meco et al., 2007Meco et al., , 2016. Because the marine terrace deposits and the two overlying storm deposits contain these taxa, these sediments are likely no younger than early Pliocene (~5.3-3.6 Ma) age, assuming no reworking. ...
The Sahara is the largest warm desert in the world, but its age has been controversial, with estimates ranging from Miocene to Holocene. Mineralogical and geochemical data show that paleosols of Pliocene to mid- Pleistocene age on Fuerteventura and Gran Canaria in the Canary Islands have developed in part from inputs of dust from Africa. These paleosols contain quartz and mica, minerals that are abundant in African dust but are rare in the basaltic rocks that dominate the Canary Islands. Trace elements with minimal mobility, Sc, Cr, Hf, Th, and Ta as well as the rare earth elements, show that paleosols have compositions that are intermediate between those of local rocks and African-derived dust. Thus, results reported here and in a recently published study by others indicate that 9 paleosols record delivery of African dust to the Canary Islands between ~4.8–2.8 Ma, ~3.0–2.9 Ma, ~2.3–1.46 Ma, and ~0.4 Ma. A long-term paleosol record of African dust input agrees with deepsea records off the coast of western Africa that imply increased dust fluxes to the eastern Atlantic Ocean at ~4.6 Ma. It is concluded that the Sahara Desert has been in existence as an arid-region dust source, at least intermittently, for much of the Pliocene and continuing into the Pleistocene.
... There is no direct evidence that Califrapana is related to Rapana. While dispersal of processors across the Pacific Ocean from east to west by equatorial countered currents during veliger stage cannot be discounted it seems more likely with the submergence of southern North America (Panamanian Seaway) currents crossed from the Atlantic to the Pacific and headed west as suggested by the dispersal of the planktonic gastropod Janthina Röding (1798) (Meco et al. 2016) during the Pliocene, but before the closure of the Panamanian Seaway. However, this also does not prevent the eastward dispersal by a northern Pacific counter current, but there is no direct evidence for this either. ...
... These eastern Atlantic/Mediterranean relationships are ancient, and probably occurred since the earliest colonisation of Santa Maria Island in the late Miocene-early Pliocene, aided by sea surface currents possibly different from the present ones, which, set in place by coeval easterly trade winds, promoted the dispersal of larvae and juveniles/small adults (these attached to rafts) of marine species from European shores towards the western Atlantic. It is known that some were able to reach and successfully colonise American Atlantic shores (Harzhauser et al., 2002;Baarli et al., 2017) and a few reached the Pacific Ocean (Meco et al., 2016) prior to the closure of the Isthmus of Panama. Thus, it is very probable that during the Pliocene, Santa Maria Island was colonised by the larvae of borers from a Mediterranean region or eastern Atlantic/Macaronesian archipelago, similarly to other Pliocene benthic organisms fossilized in the sedimentary deposits of the island Janssen et al., 2008;Winkelmann et al., 2010;Madeira et al., 2011;Á vila et al., 2012, 2015c, 2016bMeireles et al., 2012;Rebelo et al., 2014Rebelo et al., , 2016Santos et al., 2015;Johnson et al., 2017;Uchman et al., 2016Uchman et al., , 2017aUchman et al., , 2018Uchman et al., , 2020. ...
Pliocene body fossils from Santa Maria Island, Azores, have been studied for decades, but only more recently have ichnofossils received their due attention. Calcareous Pliocene deposits from the Baía de Nossa Senhora section contain numerous, diverse, well-preserved natural casts of invertebrate borings. The study of this type of fossils adds to knowledge on the dispersal of benthic faunas across oceans to volcanic oceanic islands. The borings belong to seven ichnogenera and twenty-two ichnotaxa at the ichnospecies level with more than half pertaining to Entobia, which is produced by clionaid sponges. Other borings found were produced by bivalves (Gastrochaenolites), polychaete worms (Caulostrepsis and Maeandropolydora), sipunculid worms (Trypanites), phoronid worms (Talpina) and ctenostome bryozoans (Iramena). The occurrence, ichnogeny, distribution and preservational state of the borings suggest that the bearing bioclasts have been exposed for several years on the sea floor. The borings derive from different bathymetric zones on the shelf, and their formation took place during several bioerosional phases. The association of borings belongs to the Entobia ichnofacies, which is typical of carbonate rocky shores, and shows close similarity to those described from the Paratethys, Mediterranean and partly the eastern Atlantic regions. This fits the idea that most of the Neogene shallow-water marine fauna in the Azores is biogeographically related to the eastern Atlantic shores.
... Fossil bony fishes are known from the island, but the last account for Santa Maria fossil Actinopterygii fishes dates from the 1950s and 1960s (Ferreira, 1955;Zbyszewski & Ferreira, 1962). With few exceptions Betancort et al. 2016), the majority of the published palaeoecological and palaeobiogeographical studies on the marine fauna and flora of the Macaronesian archipelagos targeted sessile or low-motility species, such as the marine molluscs, echinoderms, bryozoans, barnacles, ostracods and algae (Meco, 1977;Meco et al. 1997Meco et al. , 2015Meco et al. , 2016Ávila et al. 2008a, b, 2009a, b, 2015bWinkelmann et al. 2010;Madeira et al. 2011;Santos et al. 2011Santos et al. , 2012aMeireles et al. 2012Meireles et al. , 2014Ávila, 2013;Baarli et al. 2013Baarli et al. , 2017Betancort et al. 2014;Johnson et al. 2014;Rebelo et al. 2014;Tuya et al. 2017). Still largely unresolved, an interesting question is how the evolutionary patterns and processes inferred from these studies relate to the dispersal capabilities of species (Ávila et al. 2019). ...
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Fossil fishes are among the rarest in volcanic oceanic islands, their presence providing invaluable data for the understanding of more general (palaeo)biogeographical patterns and processes. Santa Maria Island (Azores Archipelago) is renowned for its palaeontological heritage, with representatives of several phyla, including the Chordata. Herein, we report on the fossil fishes, resulting in an increase of the number of Pliocene fishes from the Azores to 11 taxa: 7 Chondrichthyes and at least 4 Actinopterygii. The genus Sparisoma is reported for the first time in the fossil record. The presence of fossil remains of the parrotfish Sparisoma cretense in Last Interglacial outcrops is significant, because it posits a setback for the theory that most of the present-day Azorean marine species colonized the area after the last glacial episode. Our multidisciplinary approach combines palaeontological data with ecological and published genetic data, offering an alternative interpretation. We suggest that most of the Azorean shallow-water subtropical and temperate marine species living in the archipelago during the Last Interglacial were not affected by the decrease in sea surface temperatures during the last glacial episode. We also predict low genetic diversity for fish species presently living in the Azores and ecologically associated with fine sediments, due to the remobilization and sediment transport to abyssal depths, during the Last Glacial episode; these are viewed as post-glacial colonizers or as ‘bottleneck’ survivors from the Last Glaciation.
... La explicación de un enterramiento rápido por aporte de sedimentos es coherente con la presencia de otro afloramiento de bivalvos en posición de vida de la especie Lutraria oblonga (Gmelin) en la vertiente noreste de La Isleta (cantera de La Esfinge), que también contiene un nivel extraordinariamente rico en conchas del gasterópodo Janthina typica (Bronn) (Meco et al., 2016), una especie de vida pelágica y concha sumamente frágil. La conservación de este tipo de conchas se explica únicamente si su deposición está asociada a un fenómeno de enterramiento rápido, donde no se han producido procesos de retrabajamiento posterior (Brett & Baird, 1986). ...
... About 5 to 4 Ma ago, in the Early Pliocene, the earth had a warm, temperate climate (Fedorov et al., 2013). The marine waters of the Canary Islands between 4.8 and 4.2 Ma (Meco et al., 2015(Meco et al., , 2016, as well as those of the Azores (Santa Maria Island), were subtropical to warm-temperate seas (Ávila et al., 2012). The presence in the Mediterranean (Lybia) of the genera Galeocerdo, Carcharhinus, Archosargus (?) and Diodon indicates a tropical to equatorial climate (Pawellek et al., 2012). ...
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Los dientes fósiles de peces están contenidos en depósitos marinos datados en ca 4.8 Ma de las Islas de Gran Canaria y Fuerteventura (Islas Canarias, España). Estas islas, situadas en el Giro subtropical del Atlántico Norte, pueden considerarse una estación intermedia entre un Mar Caribe que estaba cercano al cierre del Paso de América Central, y el Mediterráneo en su primera etapa tras la apertura post-Mesiniense de Gibraltar. Ello permitía una comunicación pantropical para los animales del necton que eran capaces de desplazarse a grandes distancias. Se identifican por primera vez los peces Chondrichthyes Carcharocles megalodon, Parotodus benedeni, Cosmopolitodus hastalis, Isurus oxyrinchus, Carcharias cf. acutissima, Carcharhinus cf. leucas, Carcharhinus cf. priscus, Galeocerdo cf. aduncus y las species de Osteichthyes Archosargus cinctus, Labrodon pavimentatum y Diodon scillae. Se ha observado coincidencia entre los ejemplares canarios y los encontrados en las Islas Azores, las costas pacíficas de América y el mar Mediterráneo.
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La comunidad universitaria de la ULPGC, y en particular la de su Facultad de Ciencias de la Educación, rinde con La investigación acompañando a la vida Estudios en Homenaje a Emigdia Repetto Jiménez un tributo a la excepcional trayectoria docente e investigadora de doña Emigdia Repetto Jiménez (1935-2020). Estas páginas quieren ser una miscelánea en recuerdo de las múltiples dimensiones profesionales que jalonaron el discurrir de la homenajeada, desde su trayectoria docente en diferentes etapas, modalidades y ámbitos educativos, hasta su prolija mentoría en investigación, sin dejar atrás su inestimable legado en la gestión académica o su liderazgo didáctico en la creación de materiales. En definitiva, muestra un reconocimiento a la pasión de Emy por la difusión de la cultura científica.
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Two new 40Ar/39Ar 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 (2σ)* at Tamaraceite) and a middle stage (4.20 ± 0.18 Ma (2σ)* at La Esfinge in Gran Canaria Island) of Early Pliocene marine deposits in the Canary 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 4.2 Ma 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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To reconstruct changes in tropical Pacific surface hydrography, we used samples from Site 1241 (5°50'N, 86°26'W; 2027-m water depth) to establish high-resolution records of Mg/Ca and δ18O for the mixed-layer dwelling planktonic foraminifer Globigerinoides sacculifer for the Pliocene time interval from 4.8 to 2.4 Ma. An increase in average sea-surface temperatures (SSTs) (24.5°-25.5°C) between 4.8 and 3.7 Ma can probably be explained by a southward shift of the Intertropical Convergence Zone, thereby increasing the influence of the warmer North Equatorial Countercurrent. The general global cooling trend, a response to intensification of Northern Hemisphere glaciation (NHG), started at ~3.2 Ma (shown by the δ18Obenthic record) and is paralleled by tropical east Pacific cooling (indicated by SSTMg/Ca). Tropical east Pacific cooling, however, had already commenced by ~3.7 Ma, suggesting that global cooling, probably related to decreasing atmospheric CO2 concentrations, might have started well before intensification of NHG. Relative changes in local sea-surface salinity (indicated by δ18Osalinity) show a decoupling from global high-latitude processes (shown by the δ18Obenthic record). Long-term regional freshening started with decreasing SSTMg/Ca at ~3.7 Ma, suggesting that changes in the tropical wind field combined with latitudinal shifts of the tropical rainbelt were related to general decreases in tropical east Pacific SST-controlled δ18Osalinity. The similarity of Pliocene SSTMg/Ca for G. sacculifer with modern SSTs in the east Pacific, in combination with the early development of a shallow thermocline at Site 1241, gives no direct support to the idea that a permanent El Niño-like Pliocene climate might have existed during the early Pliocene.
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Many believe that the Central American Seaway closed near 4 Ma, and that that closure led to increased salinity in the Caribbean Sea and stronger Meridional Overturning Circulation in the Atlantic, which facilitated the waxing and waning of ice sheets in the northern hemisphere. We offer an alternative explanation for Caribbean salinification. The atmosphere transports approximately 0.23 Sv (1 Sv = 106 m3s-1) of fresh water (moisture) from the Caribbean to the Pacific today, but that amount varies by >20% during ENSO events. Regressions of moisture transport against the Niño-3 index, a measure of the sea surface temperature in the eastern tropical Pacific, show less moisture transport from the Caribbean during El Niño events than average. Abundant evidence indicates that at 3-4 Ma the eastern tropical Pacific was 3.5-4 °C warmer than today, and if so, an extrapolation of such regressions suggests that smaller moisture transport across Central America might account for paleoceanographic inferences of a smaller salinity difference between the Caribbean and Pacific at that time. Accordingly, that decreased salinity difference at ~3-4 Ma would not require blockage of relatively fresh Pacific water at ~2-4 Ma by the closure of the Central American Seaway, but rather would be consistent with a transition from El Niño to La Niña-like conditions in the eastern tropical Pacific around that time.
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This paper* presents a series of detailed paleogeographical analyses of the Caribbean region, beginning with the opening of the Caribbean basin in the Middle Jurassic and running to the end of the Middle Miocene. Three intervals within the Cenozoic are given special treatment: Eocene-Oligocene transition (35-33 Ma), Late Oligocene (27-25 Ma), and early Middle Miocene (16-14 Ma). While land mammals and other terrestrial vertebrates may have occupied landmasses in the Caribbean basin at any time, according to the interpretation presented here the existing Greater Antillean islands, as islands, are no older than Middle Eocene. Earlier islands must have existed, but it is not likely that they remained as such (i.e., as subaerial entities) due to repeated transgressions, subsidence, and (not incidentally) the K/T bolide impact and associated mega-tsunamis. Accordingly, we infer that the on-island lineages forming the existing (i.e., Quaternary) Antillean fauna must all be younger than Middle Eocene. The fossil record, although still very poor, is consistent with the observation that most land mammal lineages entered the Greater Antilles around the Eocene-Oligocene transition. Western Laurasia (North America) and western Gondwana (South America) were physically connected as continental areas until the mid-Jurassic, ca. 170 Ma. Terrestrial connections between these continental areas since then can only have occurred via landbridges. In the Cretaceous, three major uplift events, recorded as regional unconformities, may have produced intercontinental landbridges involving the Cretaceous Antillean island arc. The Late Campanian/Early Maastrichtian uplift event is the one most likely to have resulted in a landbridge, as it would have been coeval with uplift of the dying Cretaceous arc. However, evidence is too limited for any certainty on this point. The existing landbridge (Panamanian isthmus) was completed in the Pliocene; evidence for a precursor bridge late in the Middle Miocene is ambiguous. We marshal extensive geological evidence to show that, during the Eocene-Oligocene transition, the developing northern Greater Antilles and northwestern South America were briefly connected by a "landspan" (i.e., a subaerial connection between a continent and one or more off-shelf islands) centered on the emergent Aves Ridge. This structure (Greater Antilles + Aves Ridge) is dubbed GAARlandia. The massive uplift event that apparently permitted these connections was spent by 32 Ma; a general subsidence followed, ending the GAARlandia landspan phase. Thereafter, Caribbean neotectonism resulted in the subdivision of existing land areas. The GAARlandia hypothesis has great significance for understanding the history of the Antillean biota. Typically, the historical biogeography of the Greater Antilles is discussed in terms of whether the fauna was largely shaped by strict dispersal or strict continent-island vicariance. The GAARlandia hypothesis involves elements of both. Continent-island vicariance sensu Rosen appears to be excludable for any time period since the mid-Jurassic. Even if vicariance occurred at that time, its relevance for understanding the origin of the modern Antillean biota is minimal. Hedges and co-workers have strongly espoused over-water dispersal as the major and perhaps only method of vertebrate faunal formation in the Caribbean region. However, surface-current dispersal of propagules is inadequate as an explanation of observed distribution patterns of terrestrial faunas in the Greater Antilles. Even though there is a general tendency for Caribbean surface currents to flow northward with respect to the South American coastline, experimental evidence indicates that the final depositional sites of passively floating objects is highly unpredictable. Crucially, prior to the Pliocene, regional paleoceanography was such that current-flow patterns from major rivers would have delivered South American waifs to the Central American coast, not to the Greater or Lesser Antilles. Since at least three (capromyid rodents, pitheciine primates, and megalonychid sloths) and possibly four (nesophontid insectivores) lineages of Antillean mammals were already on one or more of the Greater Antilles by the Early Miocene, Hedges' inference as to the primacy of over-water dispersal appears to be at odds with the facts. By contrast, the landspan model is consistent with most aspects of Antillean land-mammal biogeography as currently known; whether it is consistent with the biogeography of other groups remains to be seen.
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Foraminifer count and multispecies isotopic data from Ocean Drilling Program (ODP) Sites 806 (0°N, 165°E) and 847 (0°N, 95°W) are presented for the last 6.4 m.y. Faunal evidence shows a decline of taxa of Miocene origin between 4.5 and 4.0 Ma at both sites. Prior to this decline, Globoturborotalita species and Neogloboquadrina acostaensis dominated Sites 806 and 847 assemblages, respectively. Globoturborotalitids were not replaced by other thermocline dwellers after 4.2 Ma, which suggests a deepening of the thermocline and thickening of the warm pool at Site 806. At Site 847 in the eastern ``cold tongue,'' N. acostaensis was gradually replaced by N. dutertrei. After 4.2 Ma, there was also a large increase (from 0.7 to 1.30/00) in the difference between the delta18O values of Globigerinoides sacculifer, a surface dweller, and Neogloboquadrina dutertrei, a seasonal thermocline dweller at Site 847; these data, in conjunction with faunal evidence, suggest that the temperature gradient in the upper photic zone increased significantly, largely because of subsurface cooling. The events in planktonic foraminifer evolution and ecology suggest that between 4.5 and 4.0 Ma a significant step was made toward development of the modern east-west gradient in surface hydrography. The timing of these events suggests that they were related to the closing of the Central American Seaway and subsequent changes in meridional temperature gradients and/or changes in air-sea interactions that modified tropical winds.
The rise of the Panama Isthmus was the last step in the closure of the circumtropical seaways. The closure of the Panama Isthmus had fundamental consequences for global ocean circulation, evolution of the tropical ecosystems and potentially influenced the switch to the modern 'cold house' climate mode. The Atlantic and Pacific marine ecosystems became gradually separated whereas terrestrial organisms suddenly had the means to migrate between North and South America. Combining high-resolution geochemical proxies for the closure history with data on fossil distributions and genetic data provides independent evidence on the closure history. These datasets provide new boundary conditions for Earth System models to simulate the effects of palaeoceanographic change on global climate and allow exploration of hypotheses for the Northern Hemisphere glaciation.
A successor to A Geologic Time Scale 1989 (Cambridge, 1990), this volume introduces the theory and methodology behind the construction of the new time scale, before presenting the scale itself in extensive detail. An international team of over forty stratigraphic experts develops the most up-to-date international stratigraphic framework for the Precambrian and Phanerozoic eras. A large wallchart (not available for eBook) summarizing the time scale at the back of the book completes this invaluable reference for researchers and students.
Hartungia fossils were obtained from the Upper Pliocene Ananai Formation of the Tonohama Group, at Tonohama in Kochi Prefecture, Japan. This is the first report of the occurrence of Hartungia from the Upper Pliocene of the southwestern Japan. As the result of this study, it is confirmed that these are referable to Hartungia japonica (Tomida and Itoigawa) in shell shape and in major features of its sculpture. The occurrence of this species indicates that a warm oceanic current (the Kuroshio current) strongly flowed along the Pacific coast of the southwestern Japan during the Late Pliocene.