Lecture 16

Question 1

What are the basic anatomical features of arthropods?

Answer 1

Hard segmented exoskeleton, jointed appendages, bilateral symmetry

Question 2

What factors influence arthropod preservation? Which arthropods are most
abundant and diverse, yet rare in the fossil record? Why are these arthropods
rare as fossils? What kinds of arthropods tend to be more abundant as
fossils, and why?

Answer 2

a. carbonization, compression, impression
b and c. insects because they have soft body parts
d. Any arthropod with a hard calcified exoskeleton such as crustaceans, trilobites, and ammonites

Question 3

What is molting, and why do arthropods do it?

Answer 3

most arthropods shed their exoskeleton in order to grow.

Question 4

Know the basic body segments for different arthropod groups, and which the
eyes, mouthparts, and legs tend to be attached to. Know which have
uniramous and biramous limbs, and what those are.
a. Insects: Cephalon (with eyes, one pair of antennae, mandibles and
maxillae), thorax (with 6 legs and sometimes wings), and abdomen.
b. Myriapods: Cephalon (with eyes and antennae) and multiple thorax
segments with legs.
c. Crustaceans: Cephalothorax (joined cephalon and thorax with eyes, two
pairs of antennae, mandibles, maxillae, and true limbs), abdomen.
Important group! Know what conchostrachans, ostracods, and decapods
are.
d. Chelicerates: Prosoma (joined cephalon and thorax with eyes, chelicerae,
pedipalps, and legs), opisthosoma (abdomen), sometimes a telson.
Spiders, scorpions, horseshoe crabs, eurypterids. Which of the major
body sections does the spider not have?
e. Trilobites: Know anatomy! Cephalon (with eyes, glabellum, facial suture
separating librigenia and fixigenia), thorax (with axial and pleural lobes),
pygidium.

Answer 4

remember them from ppt

Question 5

When were eurypterids common? How were they important ecologically?

Answer 5

Known also as “sea scorpions” were common during the Paleozoic era and were top predators that influenced the ecosystems by their activities on the seafloor

Question 6

Know the difference between proparian, gonatoparian, and opisthoparian
sutures in trilobites.

Answer 6

Proparian- lateral margin, posterior margin, and genal angle and spore
Gonatoparian- eye, glabeella, and fixigena
Opisthoparian- librigena, cranidium (glabella and fixigena)

Question 7

Know that trilobites were most abundant in the Cambrian and Ordovician,
but survived to the end of the Paleozoic. When were phacopines most
common? Proetids?

Answer 7

-trilobites most common in cambrian and ordovician
-Phacopines were most common in devonian period
-Proetids were most common from devonian period to the end of permian period.