Lophiodon remensis

Overview

Lophiodon remensis was a hoofed mammal that roamed Eocene Europe. It illustrates the ancient diversity of perissodactyls, the group that includes horses, tapirs, and rhinoceroses. Jaws and skulls from several European localities connect its story.^[1][2]

Key facts

Even a small jaw retaining teeth can provide a key to the body size of an ancient animal. Scientists studying Lophiodon from Geiseltal estimated changes in body mass using molar size. Interestingly, its changes differed from those of horse relatives in the same forest.^[3]

Time and place

It is known from Eocene Europe. Researchers have studied specimens from Épernay, France, dating to around 48 million years ago, and later middle Eocene material from Geiseltal, Germany. One animal offers a journey through several European fossil localities of that time.^[1][3]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

An upper jaw from Épernay, France, preserves a tooth row running from premolars to molars. The meeting of the frontal, lacrimal, and nasal bones of the skull also provides features for comparing this group. Body-size studies consider visible bone lengths alongside mass estimates derived from them.^[1][2][3]

A comparative table listing Lophiodon remensis as “Lophiodon remense” reports lower molar-row lengths of 68.5–90.5 mm for four specimens from Geiseltal, Germany. This means the first through third molars extend over about 7–9 cm.^[14]

Habitat and reproduction

A 2020 study reconstructed Geiseltal as a humid subtropical forest. Lophiodon is studied alongside the large plant-eating mammals of such forests. Imagining a forest warmer than present-day European landscapes, together with its hoofed animals, brings the fossil’s setting to life.^[3]

Fossil discovery

The upper jaw from Épernay became the neotype, a new reference specimen for comparing this species. Teeth from Belgium and skulls from Geiseltal, Germany, were also used in research. Understanding this animal involves connecting material from several localities rather than relying on one complete skeleton from one country.^[1][2]

References

1. Smith, De Wilde & Steurbaut (2004) · Primitive Equoid and Tapiroid mammals: keys for interpreting the Ypresian-Lutetian transition in Belgium · Bulletin RBINS Earth Sciences74 Supplement:165–175
2. Luke T. Holbrook (2009) · Osteology of Lophiodon Cuvier,1822 (Mammalia,Perissodactyla) and its phylogenetic implications · JVP29(1):212–230 · DOI10.1671/039.029.0117
3. Ring et al. 2020 — Divergent mammalian body size in a stable Eocene greenhouse climate
4. Smith, De Wilde & Steurbaut (2004) · Primitive Equoid and Tapiroid mammals: keys for interpreting the Ypresian-Lutetian transition in Belgium · Bulletin RBINS Earth Sciences74 Supplement:165–175
5. Ring et al. 2020 — Divergent mammalian body size in a stable Eocene greenhouse climate
6. Luke T. Holbrook (2009) · Osteology of Lophiodon Cuvier,1822 (Mammalia,Perissodactyla) and its phylogenetic implications · JVP29(1):212–230 · DOI10.1671/039.029.0117
7. Mayr2019 — The hindlimbs and relationships of Palaeotis
8. International Commission on Stratigraphy — Geological timescale
9. Houde & Haubold1987 — Restudy of Palaeotis weigelti
10. Hooker2016 — The skeleton and burrowing adaptations of the early mole Eotalpa
11. Smith, De Wilde & Steurbaut (2004) · Primitive Equoid and Tapiroid mammals: keys for interpreting the Ypresian-Lutetian transition in Belgium · Bulletin RBINS Earth Sciences74 Supplement:165–175
12. Ring et al. 2020 — Divergent mammalian body size in a stable Eocene greenhouse climate
13. Luke T. Holbrook (2009) · Osteology of Lophiodon Cuvier,1822 (Mammalia,Perissodactyla) and its phylogenetic implications · JVP29(1):212–230 · DOI10.1671/039.029.0117
14. Cuesta — Los Lophiodontidae (Perissodactyla, Mammalia) del Eoceno de la Cuenca del Duero (Studia Geologica Salmanticensia 29, 1993)

Research questions

If similar fossils differ in size, do they represent different species? A 2020 study reexamined earlier species distinctions in Geiseltal material and provisionally grouped it as Lophiodon remensis. This process considers size, individual variation, and evolutionary change together.^[3]

Observation

Examine the elongated head and the arrangement of teeth in the jaws.^[1][2]