Sunday 2 August 2009

British Wildlife: D

Dacentrurus armatus (Owen, 1875)
Stegosauridae; Ornithischia; Sauropsida; Chordata

Stegosaurs (‘roof lizards’) are a well known, familiar-looking, dinosaurs ranging from the middle Jurassic to the early Cretaceous.* The most familiar is the North American genus Stegosaurus, with its huge pentagon-shaped dorsal plates. Other species had more elongated plates, such as the African Kentrosaurus and Asian Tuojiangosaurus.

* The late Cretaceous taxon Dravidosaurus from India, known only from fragmentary remains, actually turned out to be a plesiosaur.

Europe’s stegosaurs include Lexovisaurus, the recently described Miragaia, and Dacentrurus. The latter genus, known only by a single species, D. armatus, was described by Richard Owen as Omosaurus (‘shoulder lizard’). Omosaurus turned out to be preoccupied by an extinct crocodylian, Omosaurus Leidy, 1856, so the name Dacentrurus (‘stinging tail’) was chosen.

The above fossil, photo taken at the Natural History Museum, shows various bones of the holotype of D. armatus, including the pelvis, femur and some vertebrae. Dacentrurus is often described as a ‘small’ stegosaur, but that is far from the truth: it is among the largest, at 6-10 m (20-33’), potentially larger than Stegosaurus armatus.

Great spotted woodpecker
Dendrocopos major (Linnaeus, 1758)
Picidae; Piciformes; Aves; Chordata

Most birds make distinctive sounds using their vocal chords, their songs and calls being used by birdwatchers to identify species which can be heard but not seen. A few birds, however, make characteristic sounds using other parts of their bodies: the white stork (Ciconia ciconia) clacks its beak like castanets; the snipe (Gallinago spp.) rubs its wing feathers together; and the trumpeter (Psophia spp.) from South America even emits its eponymous sound from its anus. The most well known non-vocal bird sound probably has to be that of the woodpecker.

Britain has four species of woodpecker. The aberrant wryneck (Jynx torquilla) apart, the group have long bills. Green woodpeckers (Picus viridis) rarely use their beaks for drumming, preferring to spend their time on the ground. The genus Dendrocopos, containing mostly black and white woodpeckers from across Eurasia, are classic in their wood-pecking behaviour.

I’ve seen great spotted woodpeckers, the more common and easily seen of the spotted species, in a few London parks, and are conspicuous in late winter/early spring when they hammer the trunks of large trees to construct a new hole in which to rear their young. The lesser spotted woodpecker (Dendrocopos minor) is less frequently seen, as it is small, hammers very quietly, and skulks at the tops of trees on branches that don’t easily support the weight of their great cousins. I’ve only ever once seen a lesser spotted woodpecker.

Deer (red)
Cervus elaphus Linnaeus, 1758
Cervidae; Cetartiodactyla; Mammalia; Chordata

Deer are the largest currently extant native British ungulates (hoofed animals). Before several other species were introduced at various points in human history, and since the extinction of others during glacial and interglacial periods of prehistory, only two (or arguably three) species of deer existed in the UK; the red deer and the roe deer (Capreolus capreolus), and perhaps the reindeer (Rangifer tarandus). The Romans introduced fallow deer (Dama dama), now ubiquitous in parkland. Owners of large estates in the south of England had various oriental deer species imported, such as sika deer (Cervus nippon), Reeves’ muntjac (Muntiacus reevesi) and Chinese water deer (Hydropotes inermis). All three escaped and managed to spread across the UK. Some didn’t make it very far; the centre of the Chinese water deer’s distribution is still Woburn Abbey and Deer Park in Bedfordshire where it was released, whereas sika deer reached Scotland, Wales and Cornwall at the other ends of the island.

Female red deer
Paradise Wildlife Park
May 2008

The red deer, however, is a true native, and despite threat of hybridisation from its close relative, the sika deer, it is still an awe-inspiring creature. My first truly wild red deer was seen from the train from Euston Station to Fort William in western Scotland in October 2004, when I was on the way to the island of Rum. The heads of mature stags could be seen against the moody cloudy skies of the Scottish moors and glens as we sped past. I was to get more sustained views, albeit more distantly, on the island itself when we visited the Kilmory Red Deer Project. The herd of deer on the island has been studied by the University of Cambridge since 1953, and much information on their behaviour, population dynamics and ecology has been gleaned from them since. The deer were introduced as a game species, so are not truly native, but are certainly not intermixed with sika, as their introduction predates that of Cervus nippon.

Next week, for E, we have a theropod from Vectis, a eulipotyphlan and an enormous bird of prey.

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