Lingulepsis, an inarticulate brachiopod.

1
Inarticulate brachiopods survive today with
shells very similar to those of their early
Ordovician relatives. Most use their long pedicle
to anchor themselves 10s of cm deep in the
sediment.
Lingulepsis, an inarticulate brachiopod.
2
Brachiopods are different from mollusks. They
anchor their shell to a firm ground using a
muscular stem (pedicle).
This shell shows an opening for its pedicle.
Billingsella, a Cambrian orthid brachiopod
3
The most primitive mollusks are single-valved
monoplacophorans have a conical cap-like valve.
They are probably the ancestors of all shelly
mollusks.
ventral (organs)
dorsal
4
Bivalve mollusks two valves are mirror image of
each other. Internal organs are different from
those of brachiopods. Most mollusks move around,
using their muscular foot.
5

• Mollusks a phylum which, today, spans seawater,
  freshwater and land ecosystems.
• - aplacophorans (cap-like shell)
• - pelecypods (bivalved shell)
• - gastropods (coiled shell snails none slugs)
• cephalopods
• (coiled shell nautilus
• shell shrunk to a bone octopi, scuttlefish)
• ... must have all evolved from some worm-like
  ancestor that started armoring its body.

6
Nautiloids shelly mollusks related to modern
Nautilus.
7
Nautiloids shelly mollusks related to modern
Nautilus.
Chambered shells used to control buoyancy by
filling with gas/water
8
Nautiloids shelly mollusks related to modern
Nautilus. Ordovician forms were generally
straight or gently curved, with very thick shells.
9
Whats a cephalopod, when you have no soft part?
scaphopod
Salterella, once thought to be a primitive
cephalopod, is now in its own phylum.
10
Hyoliths, conical shells with a lid, are
interpreted to be primitive mollusks which
appeared in early Cambrian times.
11
Echinoderms are a very diverse phylum. Today,
they include starfish, sand dollars, sea urchins,
sea cucumbers and crinoids (sea lilies). Most
show 5 arms or food grooves. Some are grazers,
some are predators, and others are filter feeders
(i.e. strain tiny bits of food from water).
12
Cambrian and Ordovician echinoderms rested on the
sea floor. Their plates of porous magnesian
calcite (CaCO3 with a few of Mg) were similar
to those of their descendants, but arranged less
symmetrically.
Helicoplacoids lived in shallow burrows? A food
groove spiraled down their armor-plated
football-shaped body.
13
Gogia, a filter-feeding eocrinoid with long arms,
used as baffles.
Eocrinoids gave rise to blastoids in Ordovician.
14
Crinoids (sea lilies) will become a highly
diverse group during most of Paleozoic.
Most were anchored to the sea floor.
15
Echinoderms are the closest relatives of
chordates (vertebrate animals). These two phyla
are thought to share a common ancestor, which
must already have been around during the late
Proterozoic or the Cambrian. Hemichordates are
animals that have a notochord (precursor of
spinal chord) but lack other features found in
most chordates.
16
conodonts mm-size tooth-like fossils of calcium
phosphate... can be dissolved out of limestone
and separated for analysis.
17
graptolites colonies of microscopic filter
feeding animals (hemichordates) The Cambrian
forms were attached to the sea-floor. But they
diversified into planktonic, free-floating
colonies during the Ordovician.
18
Graptolites are among the most useful index
fossils in the early Paleozoic. They are best
preserved in sedimentary rocks originally
deposited in deep water (quiet, oxygen-poor
sediments).
Because of fast turnover of species, conodonts
and graptolites make correlation possible within
2-3 million years.
Monograptus