Hoplolichas tricuspidatus Lichid Russian trilobite

Hoplolichas tricuspidatus

Class Trilobita, Order Lichida

Geological Time: Middle Ordovician

Size: Trilobite 50 mm long

Fossil Site: Asery level, St. Petersburg region, Wolchow River, Russia

Hoplolichas tricuspidatus Russian trilobiteThis Hoplolichas tricuspidatus specimen is testament to the creativity of adaptation by means of natural selection, as well as to the art of trilobite preparators. The spinous nature of the exoskeleton of this trilobite is a common phenotypic trait of members of Order Lichida (as well as Order Odontopleurida that was formerly Lichida Superfamily Odontopleuroidea); of course, spines are a common feature of trilobites from their earliest origins, and appear in diverse and elaborate displays. The selective pressure for nature’s spinous creativity was of course the Schizochroal eyes of the Devonian Phacopid trilobite Phacops ranaperpetual evolutionary arms race between predator and prey. The 100 sharp spines of this trilobite would have been a nasty morsel to even some of the newer reef system predators of the Ordovician seas, such as fish with jaws.

These images were taken some 20 years ago and have since propagated far and wide on the Internet, as well as Holochroal eye of a Platyscutellum trilobite. The facets exhibit very dense packing of small facets with a single corneal layer covering all lenses.those of Hoplolichas plautini, Hoplolichas furcifer and Metopolichas verrucosus. 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 note the near perfection of the spines. Typically in trilobite preparation, longer and fragile spines are broken off, then reattached, yielding a less slightly outcome. Legend has it the Russians used their space-age technologies to extrude these as a polymer through a fine needle. On balance, this is a magnificent trilobite rendering that does not depart to far from reality.

Also see: Russian Trilobites

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