|
 Coming
from the nearly half billion year old Lower Ordovician Wolhovian
Level deposits of the Wolchow River region near Saint Petersburg,
Russia, this is truly one of the very rarest Russian trilobites,
the Lichid, Metopolichas verrucosus. They are usually only seen
as fragments: a pygidium, a partial cepahalon, etc. In over
15 years,
this is only the SECOND the primary source of Russian trilobites
has ever had found. While not as showy as its Lichid cousins
of
the genus Hoplolichas, it  far outclasses them ALL in terms of rarity.
Notice the many tubercules present on the the cephalon, genal
spines,
and pygidium, a common trait of Order Lichida. The species name
is derived from verrucose, meaning with warty excrescences;
this one
has them in abundance.
These
images were taken some 20 years ago and have since propagated
far and wide on the Internet, as well as  those
of Hoplolichas
tricuspidatus, Hoplolichas
furcifer and Hoplolichas
plautini. It is not easy to miss
the eye lenses that very closely resemble schizochroal
eyes (with far fewer lenses than holochroal
eyes and each lens with an individual cornea) that are found
exclusively in trilobites of Order
Phacopid, Suborder Phacopina. However, the number of lenses
in this Hoplolichas are far fewer than the typical few hundred
to 700 found in Phacopina (albeit, there are some
Phacopina with greatly reduced number of lenses, apparently
an evolutionary adaptation). It is hardly unusual for the crystal
lenses to be preserved in magnificent detail in Phacopida (above
right), and the Hoplolichas eyes seen here have been manufactured
accordingly. More recently prepared Hoplolichas sport the ostensibly
correct holochroal versions with thousands of tiny lenses, as
shown above.
Also
see: Russian Trilobites |
