Leeds Geological Association

The Leeds Hippo

The LGA palaeontological icon


In 1851, workmen digging clay in Messrs Longley's brick field in Wortley, Leeds, discovered several large bones of such dimensions that "made them think they could not be Christians' bones". As a result, they were brought to the attention of Mr Henry Denny, Curator of the Leeds Philosophical and Literary Society's Museum, who identified them to be bones of the Great Northern Hippopotamus. He visited the site daily and collected many specimens by his own endeavours and "stimulated the men by the promise of pecuniary reward to increased care and search".

Although a number of small bones were destroyed before "their curiosity was excited by the discovery of the massive thigh bones", Denny gathered numerous bones and teeth which enabled him to identify the animals. There were the part remains of three hippopotami - an aged individual and two adults - an elephant and an auroch (extinct wild ox).

Later research identified the animals as Hippopotamus amphibius, Elephas primigenius and Bos primigenius.

There have always been concerns about the dating of these bones. Denny recorded that they were all discovered within a small area and that some were still articulated. He concluded that the bodies had not travelled far after death.

A workman told T. P. Teale, who went to the site with Denny, that querns had been found in an adjoining field at about the same level. He wrote a paper suggesting that the animals were alive after the last glaciation and possibly during roman times.

To resolve these queries, an adult femur was selected for dating at the Scottish Universities Research and Reactor Centre in 1975. Three methods were used and gave similar results of around 30,000 BP (radiocarbon years before present).

These results were completely unexpected as the dates fell within the Middle Devensian. Pollen and insect remains had shown that at this time the environment in England was tundra conditions in which the hippopotamus could not live.

It was suggested that, at the time of the discovery, it was the practice to coat bones with gelatine. Gelatine, being carbon-based, would introduce contamination of younger radioactive carbon into the sample, thus giving an erroneous result.

An attempt to resolve this problem was made using a molar tooth. It was hoped that material from the centre would not be contaminated. An age of greater than 40,000 BP (radiocarbon years before present) was determined.

The Hippo was thus shown to belong to the last (Ipswichian) interglacial (130,000 - 117,000 BP).