Happy Trilobite Tuesday! Trilobite fossils can be found just about everywhere across the face of the Earth. And as diverse as their locations may be, so are the types of preservation they enjoy. In the rugged Devonian hills that surround La Paz, Bolivia, small geodes are found that when carefully cracked open occasionally reveal amazing remnants of the distant past. Sometimes those geodes contain leaves or even brachiopods. On rare occasions, however, a complete trilobite is preserved. This beautiful 380 million-year-old Bouleia dangincourti shows off this unique preservation which not only exhibits the “positive” side of the specimen but also its counterpart.
Heavily armoured piscine torpedoes with fierce teeth roamed the oceans in the early days of fishes, in fact the Devonian era is called the age of fishes by palaeontologists as they had a huge burst of speciation and diversified to fill most marine ecological niches during this time. The now extinct (fortunately) class known as placodermi (plate skin in Greek) was the apex predator of these long gone waters, and thrived from 438 to 358 million years ago, dying out at the end Devonian mass extinction (one of the lesser ones).
Plesiosaurs, a group related to lizards, lived in the sea. Although plesiosaurs were not dinosaurs, they became extinct at the end of the Cretaceous, 65 million years ago, at the same time as the non-avian dinosaurs. Plesiosaurs had powerful swimming muscles attached to their expanded shoulder and pelvic bones, and they used their flippers to swim.
This Fossil Friday is Thalassomedon haringtoni, a long-necked plesiosaur with a relatively small head and many sharp teeth for seizing fishes and other marine animals. This long, flexible neck, with as many as 70 vertebrae, probably helped in grasping such rapidly moving prey.
It’s Trilobite Tuesday! Sometimes trilobites are uncovered in very unusual places. Paleontologists have traveled to the snow-capped peaks of Greenland and the tropical islands of southern Australia in their quest for these ancient arthropods. But sometimes you just have to be lucky. This 5 inch Dikelocephalus minnesotensis from the Upper Cambrian of Wisconsin was found being used as a doorstop in someone’s home about 40 years ago. It is perhaps the only complete example of this species ever found–only disarticulated heads and tails are usually discovered.
Lake Kaindy (Kazakh: Қайыңды көлі, Qayındı köli) is 400 metres long and reaches depths near 30 metres in some areas. It is 129 km ESE of the city of Almaty, Kazakhstan and is 2,000 metres above sea level. The lake is very young; it formed after the 1911 Kebin earthquake triggered a limestone landslide which blocked the gorge and flooded the trees. The trees you see in the photo are dried-out trunks of submerged Picea schrenkiana and are not yet decayed.
These denizens of the Paleozoic Era seas were surprisingly diverse
by Richard Fortey
If you had been able to scuba dive during the Ordovician Period, some
450 million years ago, you would have seen at once that the seas swarmed
These distant relatives of scorpions and spiders
cruised the primeval oceans for nearly 270 million years before
extinction finally took the life of the last trilobite about 250 million
years ago. Despite their ancient departure, the trilobites left behind a
rich fossil record in many parts of the world.
Fortey reconstructs the diverse habits practiced by the trilobites,
which contributed to their evolutionary success…
Hallucigenia is my favorite genus of extinct creatures. I think probably for how long it remained a mystery of which end of the creature was top and which was bottom, and what was front and what was back (also a gas bubble created an incorrect ‘head’ for some time too). It’s just… such a delightful little thing, and it has important to wisdom to offer.