# Palaeoloxodon mnaidriensis

Palaeoloxodon mnaidriensis is an extinct species of dwarf elephant belonging to the genus Palaeoloxodon, native to the Siculo-Maltese archipelago during the Middle Pleistocene and Late Pleistocene. It is derived from the European mainland straight-tusked elephant (Palaeoloxodon antiquus).

## Taxonomy and evolution

Palaeoloxodon mnaidriensis was first named in 1874 based on material from Mnaidra gap in Malta by Andrew Leith Adams in 1874 as Elephas mnaidriensis. The lectotype of the species is the molar tooth NHM 44304, from Mnaidra gap. The species continued to be treated as a species of Elephas by later authors (who sometimes synonymised it with the species "Elephas melitensis" previously named from Maltese material) until a 1942 posthumous publication by Henry Fairfield Osborn, which considered it a member of the genus Palaeoloxodon. Later 20th authors again considered the species a member of the genus Elephas, but by the 2000s its placement as a member of the genus Palaeoloxodon was generally accepted.
The temporal range of dwarf elephant material on Malta, including that of P. mnaidriensis, is poorly constrained, though almost certainly sometime during the Middle Pleistocene or Late Pleistocene. The evolutionary history of P. mnaidriensis on Malta is unclear, and it is possible that not all remains attributed to P. mnaidriensis on the island belong to the same species, with the species possibly being a wastebin to which all moderately dwarfed Sicilian-Maltese dwarf elephants have been attributed. Regardless of true relationships, all remains attributed to P. mnaidriensis are thought to ultimately descend from the continental European straight-tusked elephant (Palaeoloxodon antiquus).
While historically considered to have inhabited both Malta and Sicily, remains from Sicily are suggested to possibly belong to a separate species, provisionally referred to as P. cf. mnaidriensis or P. ex gr. mnaidriensis. P. cf. mnaidriensis descended from a colonisation of Sicily by the straight-tusked elephant from mainland Italy during the late Middle Pleistocene, around 200,000 years ago, which replaced the even smaller, less than 1 metre (3 ft 3 in)-tall Palaeoloxodon falconeri, which had descended from a separate colonisation of Sicily by P. antiquus several hundred thousand years prior.
The elephant species native to Malta and Sicily had reduced in body size as a result of insular dwarfism, a common phenomenon resulting from the colonisation of islands by large mammals. The much smaller body size of P. cf. mnaidriensis compared to P. antiquus, in combination with the relatively short period of time between colonisation and small body size suggests that the rate of dwarfism was relatively rapid.

## Description

P. cf. mnaidriensis has nearly 90% body size reduction compared to its straight-tusked elephant ancestor, with one estimate giving a shoulder height of about 1.8 metres (5.9 ft) and a mean body weight of about 1,100 kilograms (2,400 lb). Another estimate gives a shoulder height of 2 m (6.6 ft) and a weight of 1,700 kg (3,700 lb). Like P. antiquus the head of P. cf. mnaidriensis a well developed parieto-occipital crest at the top of the skull. The teeth are around 30% the size of those of P. antiquus. Relative to P. antiquus, the enamel of the teeth is thicker, and the density of lamellae on the teeth is higher, with the number of plates being slightly lower than those of the molars of P. antiquus. The limb bones are proportionally more robust than those of P. antiquus.

## Ecology

On Malta, the only other large mammal present aside from P. mnaidriensis was the dwarf hippopotamus Hippopotamus melitensis (at Ghar Dalam only, at the type locality of Mnaidra gap and other Maltese localities like Zebbug Cave and Benghisa Gap hippopotamuses appear to be absent from the assemblage, with the possible exception of Gandia Fissure). On Malta, remains attributed to P. mnaidriensis proper (including those from the type Mnaidra gap locality) have been found associated with much smaller dwarf elephants belonging to Palaeoloxodon falconeri (though this may indicate time averaging rather than contemporaneity), giant dormice belonging to the genus Leithia (which contains the largest dormice ever) and Maltamys, giant tortoises (Solitudo robusta) and giant swans (Cygnus falconeri) as well as other birds like cranes (Grus) and raptors.
The appearance of P. cf. mnaidriensis on Sicily marks a faunal turnover where the depauperate endemic fauna that characterised Sicily during the Early and early mid-Middle Pleistocene was profoundly altered by the arrival of some large mammals from the continental fauna of mainland Italy, including both predators (cave lions, cave hyenas, brown bears, wolves and red foxes) and large herbivores (wild boar, red deer, fallow deer, steppe bison, aurochs, European wild ass, and the hippo Hippopotamus pentlandi) which coexisted with P. cf. mnaidriensis. The larger body size of P. cf. mnaidriensis in comparison to P. falconeri is suggested to be as a result of needing to defend against predators, as well as due to the presence of other competing herbivores. Evidence has been found for at least the scavenging of the remains of P. cf. mnaidriensis by cave hyenas. Its ecology has been suggested to have been that of a mixed feeder (both grazing and browsing).

## Extinction

The timing of extinction of P. mnaidriensis on Malta cannot be constrained. The youngest records of P. cf./ ex gr. mnaidriensis are from what is now the island of Favignana off the coast of western Sicily dating to around 20,000 years ago, during the Last Glacial Maximum (though this date is likely to be a minimum age), which was connected to mainland Sicily for most of the Last Glacial Period due to lowered sea levels, as well as San Teodoro Cave in northeast Sicily, which dates to sometime after 32,000 years ago (other potential records have been indirectly dated to around 21-23,000 calibrated years Before Present based on association with dated European wild ass remains.) These individuals are estimated to have had a shoulder height of roughly 1.5 metres (4.9 ft), somewhat smaller than other described individuals of P. cf./ ex gr. mnaidriensis.