Which of the Following are the Only Extant Animals Descended Directly from Dinosaurs?

Which of the Following are the Only Extant Animals Descended Directly from Dinosaurs?

Only two animals descended directly from dinosaurs: birds and crocodiles. A few animals are the only ones that descended directly from dinosaurs, including crocodiles, birds, and Komodo dragons. These animals have remained relatively unchanged since the time of the dinosaurs and have been able to adapt and survive in today’s world. Each of these animals has certain characteristics that set them apart from other animals and make them unique.

Crocodiles are one of the most feared predators in the world, and their ancestors date back to the time of the dinosaurs. Large reptiles can grow up to 20 feet long and weigh over a ton. Crocodiles have thick skin covered in scales that protect them from injury.

They also have sharp teeth that can tear through flesh easily. Their powerful tails help them swim quickly through the water, and they use their strength to kill their prey. Birds are another animal that descended directly from dinosaurs.

Birds are descendants of a group of therapod dinosaurs called coelurosaurs. There are over 10,000 different species of birds alive today, which shows how successful they have been at adapting to changing environments. Birds have beaks instead of teeth and feathers instead of fur, and they lay eggs instead of giving birth to live as young as mammals.

Some birds can fly while others cannot, but all birds share these characteristics. Komodo dragons are perhaps the strangest-looking animal on this list, but they also descended directly from dinosaurs. Komodo dragons come from a group of therapod dinosaurs called carnosaurs.

They live on an island in Indonesia where they hunt for food using their keen sense of smell. Komodo dragons can grow up to 10 feet long and weigh over 200 pounds!


Which Extant Animal Class is Most Closely Related to the Dinosaurs?

The most closely related extant animal class to the dinosaurs is the reptiles. They share a common ancestor, and both animal groups have many characteristics. For example, both groups have a scaly skin, lay eggs, and are cold-blooded.

However, there are some key differences between the two groups. For instance, reptiles typically have four legs, while dinosaurs typically have two or more pairs of legs. Additionally, reptiles generally live on land, while dinosaurs are mostly terrestrial but include some aquatic and flying species.

Overall, the similarities between these two groups indicate that they are closely related.

What are Extant Vertebrates?

Extant vertebrates are animals that have a spine or backbone. This includes all mammals, birds, reptiles, amphibians, and fish. These animals are distinguished from invertebrates, which do not have a backbone.

There are approximately 66,000 species of extant vertebrates on Earth. The vast majority of these are fish, with over 32,000 species. There are around 10,000 species of amphibians, about 9,000 species of reptiles, and about 5,500 species of birds.

Just over 4% of all extant vertebrate species are mammals. Mammals evolved from early mammal-like reptiles during the Mesozoic Era (252-66 million years ago). The first true mammals were small creatures living in the dinosaurs’ shadows.

But after the dinosaurs went extinct 65 million years ago, mammals began to thrive and diversify. Today there are more than 5300 mammal species alive on Earth! Birds evolved from feathered dinosaurs during the Mesozoic Era as well.

The first birds were small carnivorous predators with sharp teeth and claws. But over time, they developed into the wide variety of bird species we see today – including everything from hummingbirds to ostriches! Reptiles evolved from reptile-like ancestors during the Carboniferous Period (360-299 million years ago).

Early reptiles were generally small and lizard-like in appearance. But as they diversified and adapted to different environments, they took on various shapes and sizes – from snakes to crocodiles! Amphibians also have their origins in the Carboniferous Period.

They likely evolved from a group of four-legged tetrapods called labyrinthodonts. Early amphibians were mostly large aquatic predators with razor-sharp teeth.

What is the Single Unique Characteristic That Distinguishes Extant Birds from Other Extant Animals?

The unique characteristic distinguishing extant birds from other extant animals is their feathers. Birds are the only animals with feathers, giving them many advantages over other animals. For example, feathers provide insulation against the cold, help birds to fly and aid in camouflage.

Which of the following is the Characteristic of Most Extant Reptiles And Most Extant Mammals?

Most reptiles and mammals are vertebrates, meaning they have a backbone. This is one of the key characteristics that separate these groups from other animals, like invertebrates, which do not have a backbone. In addition, most reptiles and mammals are tetrapods or four-legged creatures.

This is another key characteristic that helps distinguish these groups from others; birds are bipeds or two-legged creatures. Finally, most reptiles and mammals are endothermic, meaning they maintain their body temperature internally. This contrasts ectothermic animals like amphibians and fish, who rely on external heat sources to regulate their body temperature.

Which of These are Amniotes?

There are four main groups of land vertebrates: amphibians, reptiles, birds, and mammals. All four groups are amniotes, meaning they lay their eggs on dry land instead of in the water. This is made possible by the amniotic egg, which contains several membranes that protect the developing embryo from dehydration.

“amniotes” comes from the Greek word for “membrane.” Amphibians were the first vertebrates to evolve from fish and retain some characteristics of their aquatic ancestors. For example, most amphibians must return to water to mate and lay their eggs.

They also have moist skin that is often covered in mucus, which helps them absorb oxygen from the air. Reptiles evolved from amphibians and are distinguished by their dry scales, which provide protection from predators and help them regulate their body temperature. Like amphibians, reptiles must return to water to mate and lay their eggs.

Some reptiles, such as snakes and lizards, have lost their limbs throughout evolution. Birds evolved from a group of two-legged reptiles called theropods. Birds are characterized by their feathers, which provide insulation and allow them to fly.

Birds also have beaks instead of teeth, and they Lay hard-shelled eggs with thick membranes that prevent dehydration. Mammals evolved from a group of reptile-like animals called synapsids. Mammals are distinguished by their hair or fur, which provides:

  • Insulation protects them from predators.
  • Mammary glands, which produce milk for nursing young.
  • An enlarged brain was relative to body size (a trait known as encephalization).

Most mammals give birth to live young instead of laying eggs; however, there are a few exceptions, such as platypuses, echidnas (monotremes), and pangolins (pholidotes).

Unlike Eutherians, Both Monotremes And Marsupials

Monotremes are a type of mammal that is found only in Australia and New Zealand. These strange creatures lay eggs instead of giving birth to live young like most other mammals. Only five monotreme species are alive today, two of which are the platypus and the echidna.

Marsupials are another type of mammal found mostly in Australia, although a few species live in South America. Marsupials have a very different reproductive system from other mammals; they give birth to live young but keep them in their pouch until they are developmentally mature enough to survive on their own. There are over 300 species of marsupials alive today, including kangaroos, koalas, and opossums.

The Pharyngeal Pouches Become Functioning Gills in the

One of the most amazing things about vertebrate development is how gills form. Gills are outgrowths of the pharyngeal (throat) region that develop into respiratory organs specialized for exchanging oxygen and carbon dioxide with water. In fish and some amphibians, these gills are external structures that project from the body’s surface.

In other amphibians, such as frogs and salamanders, the gills are internalized but remain connected to the outside environment through openings in the sides of the head. The first sign of gill development in a developing embryo is the appearance of pharyngeal pouches. These are outpouchings of tissue from the embryonic throat that invade adjacent areas of the mesoderm (the middle layer of cells).

The number and position of pharyngeal pouches vary among different groups of animals, but all vertebrates have at least one pair. Each pouch gives rise to a single external gill filament in fishes and some aquatic amphibians, such as newts and salamanders. This filament consists of a thin sheet of the epithelium (skin-like tissue) supported by branching projections (filaments) of cartilage called gill rays.

Numerous blood vessels course through these filaments, providing an extensive surface area over which gas exchange occurs between water and blood passing through them. In most terrestrial amphibians, such as frogs and toads, each pouch produces two internal gill slits that open up into chambers (gill cavities) lined with thin sheets of epithelium supported by cartilage rods called gill arches. Blood vessels similar to those found in fish gills run through these arches, providing an extensive surface area for gas exchange between the air entering through the mouth or nose and blood passing through them.

Terrestrial amphibians typically close off their mouths and nostrils while underwater so that water does not enter their lungs; instead, they breathe entirely through their skin!

Which of the Following Statements About the Geographic Distribution of Marsupials is Accurate?

There are two different types of marsupials- those that live in Australia and those that live in South America. Australian marsupials include koalas, kangaroos, and wallabies, while South American marsupials include opossums and sugar gliders. Marsupials are interesting animals because they have a pouch on their stomach where they carry their young.

This is why they are also sometimes called “pouched mammals.” Female marsupials give birth to very undeveloped offspring, which then crawl into their mother’s pouch to continue developing. Most marsupial species are found in Australia, with around 70% of all species living there.

This is likely because Australia was cut off from the rest of the world for so long, allowing marsupials to evolve undisturbed by other mammal groups.

As Hominins Diverged from Other Primates, Which of the Following Appeared First?

As Hominins Diverged from Other Primates, Which of the Following Appeared First? The divergence of hominins from other primates is a great debate among anthropologists. Many theories exist about which traits appeared first and how this divergence occurred.

However, there is still much to be known about this process. This blog post will explore some of the most popular theories about which traits appeared first as hominins diverged from other primates. One theory suggests that bipedalism appeared first in hominins.

This trait would have given them an advantage in scavenging for food and escaping predators. Additionally, bipedalism would have freed up the arms for tasks such as carrying food or tools. This theory is supported by the fact that many early hominin fossils show evidence of bipedalism.

Another theory suggests that increased brain size was the first trait to appear in hominins. This would have given them an advantage in competition with other animals for resources and mates. Additionally, increased brain size is associated with increased intelligence, which would have helped early hominins to solve problems and adapt to their environment.

This theory is supported by the fact that many early hominin fossils show evidence of large brains relative to body size. It is also possible that both bipedalism and increased brain size appeared simultaneously in early hominins. These two traits may have been linked, as increased brain size would have required a change in posture for proper blood circulation (bipedalism).

Alternatively, these two traits indicate a general trend towards greater complexity in early hominins.

Examination of the Fossils of Archaeopteryx Reveals That, in Common With Extant Birds, It Had

The examination of the fossils of Archaeopteryx reveals that, in common with extant birds, it had feathers and claws on its wings. This is strong evidence that Archaeopteryx was indeed an ancestral bird. The fact that it also had teeth and a long tail suggests that it was not as well-adapted to flying as modern birds, but its anatomy shows clear signs of evolution from earlier reptiles.

Which of These Might Have Been Observed in the Common Ancestor of Chondrichthyans And Osteichthyans

If you ask most people to name a fish, they’ll come up with something like a tuna or a salmon. But there are two main types of fish: chondrichthyans and osteichthyans. Chondrichthyans include sharks, rays, and skates, while osteichthyans are bony fishes like tuna, salmon, and catfish.

Which characteristics were observed in the common ancestor of these two groups? Well, for one thing, this ancestor was almost certainly a vertebrate. That is, it had a backbone made of vertebrae.

In addition, this ancestor probably had some protective covering on its body. This could have been scaled (as in much modern-day fish) or something else entirely. This ancestor might also have had gills for breathing underwater.

However, it’s also possible that this creature breathed through its skin instead. Finally, this ancestor was likely an excellent swimmer thanks to its streamlined body and fins. In short, we are still determining exactly what the common ancestor of chondrichthyans and osteichthyans looked like.

But we can make educated guesses based on what we know about these two groups of fish today.

Jaws First Occurred in Which Extant Group of Fishes?

Jaws first occurred in an extinct group of fishes called placoderms. Placoderms were the first fish to have jaws, and they lived during the Devonian period, which was about 419 to 359 million years ago. Jaws allowed these fish to eat larger prey and helped them breathe better since they could now open their mouths wider.

Placoderms went extinct during the Permian-Triassic mass extinction, the largest mass extinction in Earth’s history.


Only a handful of today’s animals can trace their lineage to the dinosaurs. These include birds, crocodiles, and snakes. While many other animals have evolved from dinosaur ancestors, these three lineages have remained relatively unchanged for millions of years.

This is due to their successful adaptation to both terrestrial and aquatic environments. Birds are the only dinosaurs that survived the mass extinction event 65 million years ago and continue to thrive in nearly every corner of the globe. Crocodiles could also weather this event by retreating to freshwater habitats where they could avoid competition with mammals.

Snakes, meanwhile, persisted in the shadows of forests and jungles, where they preyed on small mammals and lizards. Today, all three of these groups are considered living fossils – a testament to the resiliency of dinosaur DNA.