Shared Vertebrate Characteristics and Hox Genes in Early Vertebrates

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Questions and Answers

What is a characteristic of vertebrate embryos that is not found in invertebrate chordates?

Absence of Hox genes
Presence of a four-chambered heart
Possession of a one-chambered heart
Development of neural crest cells along the neural tube edge (correct)

What is the primary function of the fin rays in vertebrates?

Regulation of embryonic body plan along the head-tail axis
Supporting the development of neural crest cells
Determining segment structures in the vertebrate body
Providing balance and propulsion during swimming (correct)

How do vertebrates differ from invertebrate chordates in terms of their Hox genes?

Vertebrates lack Hox genes, while invertebrate chordates have one or more sets
Vertebrates have one set of Hox genes, while invertebrate chordates have two or more sets
Vertebrates have a unique set of Hox genes not found in invertebrate chordates
Vertebrates have two or more sets of Hox genes, while invertebrate chordates have only one set (correct)

What is a characteristic of the circulatory system of vertebrates that is not found in invertebrate chordates?

Possession of a heart with at least two chambers (A) Signup and view all the answers

What is the embryonic source of many unique vertebrate traits?

Neural crest cells (D) Signup and view all the answers

What is a characteristic of the body plan of vertebrates?

Presence of a dorsal fin stiffened by fin rays (C) Signup and view all the answers

What is the characteristic that distinguishes vertebrates from invertebrate chordates?

Presence of a vertebral column (B) Signup and view all the answers

What is the significance of whole-genome duplication in chordate evolution?

It contributed to the development of traits and structures in chordates (B) Signup and view all the answers

What is the morphological feature that is shared between lancelets and vertebrates?

Pharyngeal slits (B) Signup and view all the answers

What is the relationship between Urochordata and vertebrates?

Urochordata is a sister taxon to vertebrates (B) Signup and view all the answers

What is the significance of Hox genes in chordate development?

They are involved in the development of the brain and nerve cord (C) Signup and view all the answers

What is the characteristic of the ancestral chordates?

They resembled lancelets with a notochord and pharyngeal slits (A) Signup and view all the answers

What is a shared, derived trait of Clade Vertebrata?

Presence of a cartilaginous cranium (A) Signup and view all the answers

Which feature describes the body plan of basal vertebrates in clade Cyclostomes?

Armoured skin with dermal bone plates (B) Signup and view all the answers

What is a notable feature of the body plan of conodonts, one of the earliest vertebrates?

Mineralized skeletal elements in their mouth and pharynx (A) Signup and view all the answers

Which group of vertebrates went extinct by the end of the Devonian period?

Armoured jawless vertebrates and conodonts (D) Signup and view all the answers

Which clade of vertebrates is characterized by the presence of jaws?

Gnathostomes (A) Signup and view all the answers

What type of vertebrates make up around 99% of all living vertebrates?

Amphibians (B) Signup and view all the answers

What is the primary structural protein found in the extracellular matrix of animals?

Collagen (A) Signup and view all the answers

What is a shared, derived trait of Clade Gnathostomes that allows them to capture and process diverse foods?

Opposing jaws that open/close the mouth forcefully (C) Signup and view all the answers

Which type of ossification is responsible for the formation of dermal skeletal structures in vertebrates?

Intramembranous ossification (C) Signup and view all the answers

What type of bones are present in the vertebral column of early vertebrates like conodonts?

Endoskeletal bones (B) Signup and view all the answers

What is the characteristic of the fossil record of early gnathostome vertebrates from the Silurian-Devonian periods?

Diverse array of extinct armoured vertebrate fish (C) Signup and view all the answers

What is the characteristic of extant Chondrichthyans that distinguishes them from other vertebrates?

Cartilaginous skeleton (C) Signup and view all the answers

What is the term used to describe the 'plate-skinned' extinct armoured vertebrate fish?

Placoderm (C) Signup and view all the answers

What is the difference between endoskeletal and dermal bones in vertebrates?

Endoskeletal bones are internal, while dermal bones are external (B) Signup and view all the answers

What is the characteristic of the dermal skeletal structures in living vertebrates?

Retained in facial and pectoral bones, and teeth (B) Signup and view all the answers

What is the evolutionary significance of the development of jaws in vertebrates?

It allowed for the capture and processing of diverse foods (C) Signup and view all the answers

What is the name of the extinct placoderm fish that was approximately 10 meters in length?

Dunkleosteus (C) Signup and view all the answers

What is the characteristic of Clade Gnathostomes that distinguishes them from other vertebrates?

Presence of jaw (C) Signup and view all the answers

What is a characteristic of the skeleton of gnathostomes?

It is mineralized, including mineralized teeth. (C) Signup and view all the answers

What is the likely reason for the evolution of larger and wider mouths in early gnathostomes?

To enable the capture of larger prey. (B) Signup and view all the answers

What is the result of genome duplication in gnathostomes?

The duplication of Hox genes. (A) Signup and view all the answers

What is the function of the lateral line system in aquatic gnathostomes?

To detect vibrations in the water. (D) Signup and view all the answers

Which of the following is a characteristic of the forebrain in gnathostomes?

It is associated with enhanced smell and vision. (B) Signup and view all the answers

Study Notes

Vertebrate Characteristics

Vertebrates have two or more sets of Hox genes, likely originating from whole-genome duplication, whereas invertebrate chordates (lancelets and tunicates) have only one set of Hox genes.
Hox genes regulate the embryonic body plan along the head-tail axis, determining segment structures.
Neural crest cells develop along the neural tube edge in vertebrate embryos and migrate within the embryo, contributing to structures such as teeth, certain skull bones/cartilage, and diverse types of neurons (nerves).
Dorsal, anal, and tail fins are stiffened by fin rays along the centerline in vertebrates.
Vertebrates possess a modified, complex circulatory system with a heart having at least two chambers.

Early Vertebrate Evolution

Conodonts were among the earliest vertebrates in the fossil record, dating from 200–500 million years ago.
Conodonts had cartilaginous cranium and vertebral column, were jawless, but possessed mineralized skeletal elements in their mouth and pharynx.
Other groups of jawless vertebrates were armoured with defensive plates made of dermal bone on their skin.
All early vertebrate groups, including conodonts and armoured jawless vertebrates, went extinct by the end of the Devonian period, following the evolution of jawed fish.

Clade Gnathostomes

Gnathostomes are a clade of vertebrates that have jaws, with ~99% of all living vertebrates being gnathostomes.
Gnathostomes include sharks and their relatives, ray-finned fishes, lobefinned fishes, amphibians, reptiles (including birds), and mammals.
Gnathostomes have opposing jaws that open/close the mouth forcefully to capture and process diverse foods.
Gnathostomes exhibit a mineralized skeleton, including mineralized teeth.
Gnathostomes have two pairs of lateral appendages, such as fins or legs.
Gnathostomes have an enlarged forebrain, which is associated with enhanced smell and vision.
Aquatic gnathostomes possess a lateral line system that detects vibrations in the water.

Origin of Jaws and Mineralization of the Skeleton

The earliest vertebrates likely had cartilaginous skeletons.
The dermal skeletal structures are derived from intramembranous ossification (not from preformed cartilage).
Formed external armor in early armored fishes, and is retained in living vertebrates, such as bony fin rays in fish, facial and pectoral bones, and teeth.

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Description

Explore the shared, derived traits of vertebrates and the presence of multiple sets of Hox genes, likely from whole-genome duplication. Learn how Hox genes regulate the embryonic body plan and determine segment structures. Delve into neural crest cell development and more in this quiz.