The Miocene landscape of continental Spain

The Miocene landscape of continental Spain
Somosaguas
Reconstruction of Madrid’s Middle Miocene site, at Somosaguas.

This new painting it’s the first price winner of the illustration contest: “Viajando a tiempos pretéritos”, organized by the “Geodivulgar Group”, from the Complutense University of Madrid.

For the contest I had to draw a Miocene continental landscape, so I choose to reconstruct a fossil site in which I had worked before, the Somosaguas Site, in Madrid (Middle Miocene – 14 Ma). I tried to show three main features of this miocene landscape: Geology, flora and fauna.

Geology

In the Somosaguas fossil site there are three different strata, only two of them contain fossils. For the painting I choose to represent the only one with a mega-faunal assemblage, the uppermost-strata (T3, in the papers) (Hernández Fernández, et al., 2006). This layer has been interpreted as the distal part of an alluvial fan, this fan would see the formation of small ephemeral lake systems. Knowing this, I looked for pictures of alluvial fans, mainly from the Death Valley, in order to draw a similar morphology in the background of the drawings. For the mountains I painted a slightly different version of the familiar Madrid´s granitic range.

Flora

The fossil-bearing layer in the Somosaguas fossil site represents a Savanah biome, in a tropical semi-arid climate with a strong seasonality. Thanks to palynologycal analysis from various Middle Miocene sites in Madrid (Fernandez-Marrón, et al., 2004), we know that the granitic mountains were covered with Pinus, Tsuga, Fagus, Zelkova and Ilex. For the painting I focused mainly on the pine trees, maybe under the influence of the current look of this mountain range.

Somosaguas-diagram.png
Some examples of pollen grains found in Madrid’s Miocene sedimentary rocks. Green for high elevation flora, yellow for the grasslands components and blue for the riparian vegetation. The grain pictures are mine. 

The vegetation in the alluvial fan would have been xeric, forming open grassland with small shrubs such as Podogonium (Miocene Fabaceae), Pistacia, Robinia, Ephedripites, Asteraceae, Ericaceae and grasses (Poaceae).

Close to the small ponds some form of riparian vegetation could develop, mainly Salix, Carya, Alnus and Daphnogene.

Fauna

This fossil site provides paleontologists in Madrid with fossils from a very complete Miocene faunal assemblage. The principal components are Gomphotherium angustidens, Anchitherium sp, Prosantorhinus douvillei (among others). The carnivores are represented mainly by Hemicyon and the great Bear-Dog: Amphicyon. Also, thanks to a very extensive work carried out mainly by students, lots of microvertebrate fossils have been found in the sediment range (Hernández Fernández, et al., 2006).

In contrast to a very extensive faunal list, the painting here seems to be a bit empty. I wanted to focus mainly on the landscape and thus I paid a lot of attention to the sky, mountains and background. The only animals represented in the picture are a small herd of Gomphotherium angustidens, drinking from the small ponds that would form in the distal region of the alluvial fans during the wet season. The Gomphotherium is usually advertised as the face of the Somosaguas site, and their size (more than 3m height) would have made them a landscape feature more than anything.

By combining these three features I hope to have created a faithful reconstruction of Madrid’s landscape during the 14 million years ago.

Fernández Marrón, M.T., Fonollá Ocete, J.F. Sesé Benito, C. & Jiménez Rodrigo, J.C. Estudio paleomabiental de nuevos yacimientos de plantas y vertebrados de la “Unidad Intermedia” del Mioceno Medio de la cuenca de Madrid. Revista Española de Paleontología, 19, 2, 199-213.

Hernández Fernández, M., Cárdaba, J.A., Cuevas-González, J., Fesharaki, O., Salesa, M.J., Corrales, B., Domingo, L., Elez, J., López Guerrero, P., Sala-Burgos, N., Morales, & López-Martínez, N. 2006. Los yacimientos de vertebrados del Mioceno medio de Somosaguas (Pozuelo de Alarcón, Madrid): implicaciones paleoambientales y paleoclimáticas. Estudios Geológicos, 62, 1, 266-294.

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Reconstruction of the Cortes de Arenoso Site (Spain, Utrillas Group, Albian).

Reconstruction of the Cortes de Arenoso Site (Spain, Utrillas Group, Albian).

As promised, this reconstruction is focused in the vegetation rather than the animals. I made this piece in 2015 for my Master’s Thesis. It features a wet interdune, a pond between desert dunes with enough water and humidity to allow the presence of vegetation. I took inspiration from the wet interdunes of Namib’s desert and the Lençóis Maranhenses’s National Park at Brazil.

reconstruccion-tfm
A wet interdune from the Albian of Spain.

This reconstruction is not based on macrofossils from plants found at the site. Instead, I carried out a palinological study. I spent days looking at fossilized pollen and spores found inside the Utrillas sandstones. The Utrillas Group is a large unit of sandstones and clays of mainly Albian age. In recent years it has been interpreted as dune and interdune deposits.

 

unnamed
The outcrop. The white sands are the dune deposits of the Utrillas Group. (Cortes de Arenoso, Castellón).

There are two vegetation groups featured in the picture: The plants found inside the wet interdune and those found outside, which can be seen beyond the dunefield.

Inside the wet interdune, and near the pond I placed the most representative families found in the samples. These are mainly ferns and angiosperms, which would need high levels of humidity. You can see some Cupressaceae plants and cykas, less frequent in the samples.

Outside the interdune and near the coast with the Tethys Ocean, the top of Auracariaceae and Cheirolepidiaceae trees can be seen. These trees are placed near the coast as they thrive in salt-rich soils. Not featured in the picture are the pines and other conifers, which would grow at the mountain ranges at the other side of the dunefield.

reconstruccion-esquema
1- Auracariaceae & Cheirolepidiaceae. 2- Cupressaceae. 3- Cycadales/Bennettitales. 4- Ferns (Cyatheaceae, Dicksoniaceae, Schizaeaceae & Gleeicheniaceae). 5- Angiosperms (Chloranthaceae).
diagrama-autoctonos
A figure from my Master’s Thesys. It shows the vegetation inside the interdune and their pollen or spores. Mind the spanish.

This vegetation points to a hot and arid climate. Which could mean that the dunes were part of a much larger desert system.

Two Coloborhynchus are flying over the dunes. This pterosaur is found in England, North Africa, South American and Brazil. It has not been found in Spain but it probably flew over the dunes on their migratory paths.

Next entry: Back to dinos!

Sources:

Altolaguirre, Y. (2015): Estudio palinológico preliminar del Cretácico Inferior de la sección de Cortes de Arenoso (Castellón). (Master’s Thesys) 59.

Rodríguez‐López, J. P., Melendez, N., de Boer, P. L., & Soria, A. R. (2012): Controls on marine–erg margin cycle variability: aeolian–marine interaction in the mid‐Cretaceous Iberian Desert System, Spain. Sedimentology, 59(2), 466-501.