Among My Trilobites

AMONG MY TRILOBITES

THE ORDOVICIAN PART 1

The Ordovician period lasted from 504 to 441 million years ago. It was named for an ancient Welsh tribe, the Ordovices. Trilobites from what would later become Russia developed unusual shapes, some with eyes on long stalks, others with jagged spines. The Ordovician ended with the biggest Ice Age in Earth's history, wiping out many families of trilobites.

TO LEARN MORE ABOUT EACH ORDER OF TRILOBITES, CLICK ON
IT'S NAME. THIS WILL TAKE YOU TO SAM GON'S WEBSITE FOR A
DESCRIPTION. USE YOUR BROWSER'S BACK BUTTON TO RETURN
TO THIS PAGE.

ASAPHIDA ORDER

Superfamily: Asaphoidea

Family Asaphidae
Subfamily Asaphinae

Asaphid evolution has been fairly well studied in the area near St. Petersburg in Russia with the following relationships felt to exist:

5cm Volchow River, St. Petersburg, Russia

Lepidurus is one of the oldest is this area, found in Volhovian level sediments of the Lower Ordovician Age. Its descendants included several different lines of development. One its earliest descendants is a line that ended with A. raniceps, found in Lower Ordovician sediments at the Kunda level:

8.2cm Volchow River; St. Petersburg, Russia

Another group of descendants included a wide variety of groups, found in the Asery Level Mid-Ordovician sediments. One line included
Asaphus kotlukovi:

5cm Lower Asery Level, Volchow River, St. Petersburg, Russia

This trilobite gave rise to the next species, A. punctatus:

6cm Lower Asery Level, Volchow River, St. Petersburg, Russia

And the next step in the sequence was A. intermedius:

8cm Volchow River, St. Petersburg, Russia

Another branch of the family resulted in A. platyurus:

7.5cm Volchow River; St. Petersburg, Russia

Yet another branch gave rise to A. cornutus:

8.7cm Volchow River, St. Petersburg, Russia

Now this gave rise to a pair of divergent lines. One included A. holmi:

7cm Volchow River, St. Petersburg, Russia

And A. holmi begat A. latus:

6.5cm Volchow River, St. Petersburg, Russia

The other line from A. cornutus developed into A. kovalevski:

6cm (+ eye: 1.5cm) Volchow River; St. Petersburg, Russia

I'll put more species into this line-up as I acquire them. My source for these relationships is the St. Petersburg Paleontological Laboratory's chart, which is no longer available on their website, so I'll have to find some other way to display it here.