Friday, 4 July 2014

Mosses from Late Eocene Rovno Amber.

Mosses are thought to be among the most ancient of plant groups, and still make up a significant proportion of all plant communities. They are an ancient group, considerably predating vascular plants such as Ferns and Seed Plants, but they have a poor fossil record, largely due to their lack of easily preserved hard tissues. Almost all known Tertiary Moss fossils are from amber (preserved tree resin) mostly from Late Eocene Baltic Amber, and Oligocene Saxonian Amber. Rovno Amber originates from the Early Oligocene Mezhygorje Formation in the Ukriane, though studies of Insects from this amber suggest that it is Late Eocene in origin, contemporaneous with Baltic Amber.

In a paper published in the journal Arctoa on 26 December 2011, Michael Ignatov of the Main Botanical Garden of the Russian Academy of Sciences and Evgeny Perkovsky of the Schmalhausen Institute of Zoology of the Ukrainian National Academy of Sciences, describe a series of Moss specimens from Rovno Amber. 

Ignatov and Perkovsky acknowledge that accurate identification of moss species is often impossible without their sporing bodies, and that recent genetic studies have suggested traditional classification schemes for Mosses are somewhat inaccurate, and that the classification assigned to the Rovno Amber specimens must therefore be treated with some caution. They also note that Mosses found as inclusions in amber were almost certainly growing on tree-trunks prior to their preservation, and that tree-trunk mosses are often somewhat smaller than members of the same species growing in other environments.

The first two specimens originate from the Pugach Quarry at Klesov, and are assigned to the extant species Hypnodontopsis mexicana, which is found in modern Mexico, but which is also common in Baltic Amber.

 
Specimens of Hypnodontopsis mexicana from Rovno Amber. Ignatov & Perkovsky (2011).

The next specimen is assigned to the species Hypnodontopsis pilifer, which has only previously been described from Baltic Amber. This specimen also comes from the Pugach Quarry.

Specimen of Hypnodontospis pilifer from Rovno Amber. Ignatov & Perkovsky (2011).

The next specimen is placed in a new species and given the name Neckerites pusillus; ‘Neckerites’ means ‘similar to Neckera’ (an extant genus of Mosses), but no explanation of ‘pusillus’ is given. It is presumed to be a member of the family Neckeraceae, which is widespread in temperate to sub-tropical climates today, but which has not been recorded from Baltic Amber.

Specimen of Neckerites pusillus from Rovno Amber. Ignatov & Perkovsky (2011).

The next specimen is placed in the extant genus Palamocladium, and given the specific name fossile (fossil). Modern members of the genus Palamocladium are found throughout the tropics, and as far north as the southern US, southern Japan and the Caucasus Mountains. The genus has not been described from Baltic Amber, however there are undescribed specimens which appear quite similar.

Specimen of Palamocladium fossile from Rovno Amber. Ignatov & Perkovsky (2011).

The next two specimens are assigned to the extent species Ctenidium capillifolium, which today is found in China, Japan and Korea, and which has also been recorded from Baltic Amber.

Specimens of Ctenidium capillifolium from Rovno Amber. Ignatov & Perkovsky (2011).

The next specimen is assigned to the species Isopterygium minutirameum, which is found throughout the tropics today. This is the first known fossil assigned to the genus Isopterygium

Specimen of Isopterygium minutirameum from Rovno Amber. Ignatov & Perkovsky (2011).

The next two specimens are placed in the genus Sematophyllites, and given the specific name subjulaceius, which is not explained. Other members of the genus Sematophyllites are known only from Baltic Amber.

Specimens of Sematophyllites subjulaceius from Rovno Amber. Ignatov & Perkovsky (2011).

The next specimen is placed in the species Tristichella glabrescens, which is found in Japan and the Philippines today and which has been recorded from Baltic Amber.

Specimen of Tristichella glabrescens from Rovno Amber. Ignatov & Perkovsky (2011).

Finally Ignatov and Perkovsky record a single specimen of an unknown Moss. This does not appear to be a member of any known species, but is poorly preserved so Ignatov and Perkovsky refrain from describing it as a new species.

Unknown Moss from Rovno Amber. Ignatov & Perkovsky (2011).

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