Question

Match the organisms with the appropriate description. ____________tunicates __________ fishes __________amphibians __________primates __________birds ________monotremes __________marsupials ___________placental ____________mammals ________australopiths a. pouched mammals b. invertebrate chordates c. feathered amniotes d. egg-laying mammals c. extinct hominins f. have grasping hands with nails \(g\). first land tetrapods h. most diverse mammal lineage i. oldest vertebrate lineage

Short answer

1-b, 2-i, 3-g, 4-f, 5-c, 6-d, 7-a, 8-h, 9-c.

Step-by-step solution

Identify the Correct Descriptions

Before matching, read each description carefully and note any keywords or unique identifiers that can be linked to each organism group.

Match Tunicates

Tunicates are invertebrate chordates, hence they match with description (b). Match: tunicates - b.

Match Fishes

Fishes are considered the oldest vertebrate lineage, so they match with description (i). Match: fishes - i.

Match Amphibians

Amphibians are known as the first land tetrapods, aligning them with description (g). Match: amphibians - g.

Match Primates

Primates have grasping hands with nails, making them a fit for description (f). Match: primates - f.

Match Birds

Birds are characterized as feathered amniotes, placing them with description (c). Match: birds - c.

Match Monotremes

Monotremes are egg-laying mammals, so they correspond with description (d). Match: monotremes - d.

Match Marsupials

Marsupials are known as pouched mammals, thus they should be matched with description (a). Match: marsupials - a.

Match Placental Mammals

Placental mammals are noted for being the most diverse mammal lineage, so they align with description (h). Match: placental - h.

Match Australopiths

Australopiths are described as extinct hominins, linking them with description (c). Match: australopiths - c.

Key concepts

Chordates

Chordates are a diverse group of animals characterized by having, at some stage in their life, a notochord. The notochord is a flexible rod-like structure that provides support. Chordates also possess a nerve cord running along their back, pharyngeal slits, and a post-anal tail. These features might not be visible in adult animals, but they are present during embryonic stages.
One key subgroup of chordates is vertebrates. Vertebrates have a spine or backbone, which is an enhancement of the notochord feature. Another example of chordates includes tunicates, which are fascinating as they display the typical chordate characteristics mainly in their larval stage. As adults, tunicates are invertebrates—known as sea squirts—that filter-feed through a siphon. It is this variety among chordates that makes them a particularly interesting group to study.

Mammalian Characteristics

Mammals are a group of warm-blooded vertebrates that have certain defining characteristics. Primarily, mammals are known for possessing mammary glands, which produce milk to feed their young. This is a feature unique to mammals and is directly tied to the success of their offspring.
They also typically have hair or fur, which provides insulation from the cold. Most mammals have a well-developed brain, allowing for complex behaviors compared to other animals. Commonly, mammals have three middle ear bones that help in improved hearing abilities. Furthermore, the presence of a diaphragm assists in efficient respiration, further distinguishing them from other vertebrates.

• Monotremes: These are egg-laying mammals, which are quite rare.
• Marsupials: Characterized by birthing underdeveloped young that often mature in a pouch, such as kangaroos.
• Placental Mammals: They give live birth, after long gestation periods within the uterus, enabling better-developed young at birth.

Vertebrate Lineages

The lineage of vertebrates spans many millions of years and includes a wide variety of life forms. The earliest vertebrate fossils are fish, which are the oldest known vertebrates. These aquatic animals marked the beginning of vertebrate evolution.
Over time, tetrapods evolved, marking an essential transition from life in water to life on land. Amphibians were likely the first among the tetrapods to colonize terrestrial habitats. Later evolutionary developments led to reptiles and subsequently mammals and birds. This transition from water to land and adaptations concerning respiration and locomotion significantly shaped the vertebrate lineage.

• Fish: The first vertebrates, crucial in understanding the evolution of aquatic to terrestrial life.
• Amphibians: They bridge the gap between aquatic and terrestrial environments.
• Birds and mammals: Represent advanced forms with adaptations for diverse habitats.

Hominins

Hominins refer to a group within the primate order that includes modern humans and their ancestors. This lineage is significant due to its evolutionary changes that led to modern human behavior and anatomy. Hominins are distinct in their bipedal locomotion, meaning they primarily walk on two legs. This trait is one of the first major steps that occurred in the evolution of hominins beginning approximately 7 million years ago.
Australopithecines, for instance, are a primitive group of hominins that displayed both ape-like and human-like features. Over time, the evolutionary journey of hominins saw significant developments such as increased brain size, use of tools, and complex social behaviors. These aspects are essential in studying human evolution, as they offer insights into how humans evolved to what they are today.