Species Fossils
Receptaculites: Algae or sponges ?
Time : Receptaculites appeared around 488 million years ago in the Lower Ordovician and disappeared 250 million years ago in the Lower Triassic. Their modern-day cousins, the Dacycladacae, are algae that also form globulous calcareous skeletons.
Features : Association ot a specific family is still ambiguous. At first, they were classified as sponges. They have been associated with Dacycladacae for a long time and more recently, they were compared to some sponges again.
Stromatoporoids: rough sponges
Time : Stromatoporoids appeared around 570 million years ago in the Lower Cambrian and disappeared around 140 million years ago in the Upper Jurassic.
Features : Stromotoporoids, together with corals, formed the first reefs. Stromotoporoids formed colonies ranging from a few centimetres to one metre long. Today's bathroom sponges are indirect descendants of the Stromatoporoids, which had a mineralized skeleton. Stromatoporoids would be the first multicellular animals.
Time: Coral appeared around 478 million years ago, in the Lower Ordovician; groups identified in Témiscamingue disappeared about 225 million years ago in the Upper Triassic.
Features: Sea anemones are closely related to Paleozoic corals, while jellyfish are distant relatives. Coral is a very primitive animal consisting almost exclusively of a large stomach with an opening that serves both as mouth and anus. It represents an early stage of the human egg, the stage represented by two tissues and a gastrular depression. Corals dwell on the floor of shallow tropical seas, to which they are attached; the fact that they were so common in Témiscamingue supports the theory of continental drift. There were two major types of coral in Témiscamingue: solitary or rugose corals, inhabited by a single animal, and tabulate corals, which were colonies inhabited by several individuals. Tabulate corals included the Favosite, Halysite and Syringoporus genera.
Time: Brachiopods appeared around 570 million years ago in the Lower Cambrian. Formerly very numerous (30,000 species have been identified so far), they number about 250 species today, having generally been replaced by bivalves such as oysters and mussels. Brachiopods and bivalves have many similarities (both have a two-valved shell), but are not closely related.
Features: Several new organs made their appearance with the brachiopods: liver, embryonic kidneys, a primitive heart consisting of a somewhat swollen blood vessel that is able to contract. Brachiopods feed on suspended particles by drawing in water, which carries the particles to their mouth. They live in groups but not in colonies. The brachiopods of Témiscamingue measured between 0.1 and 5 cm in length.
Time: Gastropods appeared in the marine environment around 570 million years ago, in the Lower Cambrian, and eventually spread to land and lake environments. The gastropod class includes a wide variety of contemporary species including snails and slugs.
Features: Gastropods secrete a single-valve, mineralized calcareous shell. The spiral shape makes the shell strong and compact. The animal's viscera are also arranged in a spiral and the anus is located above the head. Eyes, gills and a moving foot appeared with the gastropods; a double-chambered heart and a nervous system including several ganglia were improvements on organs that already existed in lower animals. In Témiscamingue, gastropods measured between 0.5 and 20 cm in length. They lived in the sea and probably moved by crawling along the sea floor. Some were herbivores; others were predators or scavengers.
Time: Cephalopods appeared around 523 million years ago, in the Lower Cambrian, and are found today in all warm and cold seas.
Features: The Orthoceras nautiloid was a shelled octopus. The shell probably increased by one stria every day and one chamber every 28 days; the animal lived in the most recent chamber. In Témiscamingue, Orthoceras nautiloids ranged from 5 cm to 3 metres long. They have a siphon that fills the empty chambers up with nitrogen and a funnel allowing them to eject a stream of water outwards. Nautiloids were the first great marine carnivores capable of swimming freely. Thy had a real head with a central brain and large salivry glands. Today's nautilus is a direct descendant of the Nautiloid, while octopi and squid are indirect descendants.
Trilobites: Many-Legged Creatures with a Three-Lobed Shell
Time: Trilobites appeared about 570 million years ago, in the Lower Cambrian, and disappeared about 240 million years ago in the Lower Triassic. Insects, lobsters and spiders resemble trilobites and are descended from the same ancestral branch.
Features: In Témiscamingue, trilobites varied from 0.5 to 20 cm long. Their antennae and feet were not mineralized and were rarely preserved. However, disjointed parts of their shells - which they shed like today's crustaceans - are often found. While some trilobites were predators or scavengers, most fed on floating particles or particles extracted from marine mud.
Ostracods
Time: Ostracods also appeared around 570 million years ago (in the Lower Cambrian) and are still present in today's marine plankton.
Features: Ostracods are among the first crustaceans. They are protected by a bivalve shell which is rarely more than 1 or 2 mm long; however, some fossil Ostracods from Témiscamingue were dinosaur plankton ! They could reach up to 7mm in length. (Leperditida fabulina). Ostracods are filterers that feed on particles suspended in the water.
Time : Echinoderms appeared about 570 million years ago, in the Lower Cambrian; several species still exist today. Crinoids (a kind of sea lily very common in ancient Témiscamingue), starfish, sea urchins and sea cucumbers are echinoderms. According to a recent hypothesis, ancient echinoderms related to the Mycrocystella genus gave rise to groups of fishes, which in turn gave rise to the first amphibians, distant ancestors of human beings.
Features : Crinoids are the most numerous class of echinoderm found in Témiscamingue. Although they look like plants, they are genuine animals with three nervous centres. As suspension feeders, they use ciliated cells along their arms, which are often shaped like threads, to direct particles to their mouth. Crinoids formed vast prairies in the shallow waters of Ordovician-Silurian seas.