Amber acts like a time capsule because animals and plants of the past have been preserved in this primeval tree resin for millions of years. Now paleontologists have discovered a species of animal in pieces of amber from Ukraine and the Baltics that they would not have expected to find in Europe. These are 35 million year old harvestmen from a group that was previously only known from East Asia and North and Central America. A strikingly ornamented body and grid-like projections in the head area are typical of these exotic arachnids. The first record of these harvestmen in Europe could help clarify where the ortholasmatine subfamily originally arose – and it closes a huge geographical gap.
Harvestmen are a species-rich group of arachnids that occur almost worldwide and were widespread millions of years ago. However, there is one Weberknecht group that has puzzled paleontologists for a long time: the Ortholasmatinae. “This subfamily includes some of the most amazing-looking harvestmen,” explain Christian Bartel from the Bamberg Natural History Museum and his colleagues. “They have very complex and branched eye hills in combination with a unique microstructured dorsal surface.” The entire dorsal side of the body is covered with ribs, spines and other ornaments. These harvestmen also have numerous, sometimes lattice-like, appendages on their heads. The strange thing, however, is that this subfamily of Ortholasmatinae occurs in East Asia as well as in North and Central America. However, there has been a lack of modern or fossil evidence of these harvestmen from Central Asia and Europe. This raised the question of how this difficult-to-explain distribution mishap and the large geographical gap in between came about.
Unique for Europe
Now two surprising finds in 35-million-year-old amber provide a possible solution to this mystery. Bartel and his team have discovered two representatives of the Ortholasmatinae in pieces of amber from Ukraine and the Baltics – this is the first evidence of members of this harvestmen subfamily in Europe. “The detection of an ortholasmatine harvestman in European amber deposits surprised us. Apparently, 35 million years ago, at the time of the Eocene, these harvestmen were significantly more widespread across the northern hemisphere of the earth than they are today,” says Bartel. These finds provide the first evidence that these harvestmen still existed in Europe in the Eocene, but later died out. At the same time, they could help to clarify a long-standing controversial question: Did this subfamily of harvestmen originally arise in the New World or do they have an Asian origin – so far there are contradicting views on this. “A key question is therefore whether the new finds are more similar to the Asian or the American Ortholasmatinae,” write the paleontologists.
To clarify this, Bartel and his team examined the amber pieces and their contents using high-resolution computer tomography. These scans made it possible to recognize even the animals’ fine structures. It turned out that the animals preserved in amber have characteristics that were not previously known from any other member of this harvestmen subfamily. “The structuring of the upper side of the body observed in these fossils is unique: It consists of thread-like structures that form an irregular network similar to mushroom threads, as well as structures that are reminiscent of a log bed, supplemented by some nodular elevations,” is how the paleontologists describe the appearance of the newly discovered harvestmen. “This particular structure could have given the animals both mechanical stability and lightness under their specific living conditions.”
Insight into the origin of the Ortholasmatinae
Due to their unique characteristics, paleontologists assign the amber harvestmen to a separate species and even genus: Balticolasma wunderlichi. Comparing this new species with those previously known from East Asia and the Americas, the team found: “Balticolasma wunderlichi appears to be closer to the Asian species, although many of its features reflect a simpler condition.” This could indicate that the Ortholasmatinae group originally evolved in Asia – perhaps even in western Asia and Europe. It is possible that these harvestmen were spread over much of the northern hemisphere before the Atlantic was formed and only separated when the ocean opened up. The subsequent disappearance of the European and Central Asian representatives of this group could be explained by a change in climate: “According to our model, a large proportion of the water- and heat-loving forms, including the species described here, died out as the climate became drier and colder,” write the paleontologists. While the Ortholasmatinae harvestmen of East Asia and North America were able to move south, the European species apparently were unable to do so – and they died out.
Source: Christian Bartel (State Natural Science Collections of Bavaria (SNSB) – Natural History Museum Bamberg) et al., Acta Palaeontologica Polonica, doi: 10.4202/app.01283.2025