Terror Birds – Prehistoric Nightmare!

by Sankalan Baidya

Terror birds were nothing short of a nightmarish fantasy beast that you would definitely not want to coexist with.

Yes, they used to have feathers and their feet resembled that of Tyrannosaurus Rex’s feet. They had mighty hooked beaks that could easily sever a horse’s spinal cord with a single blow.

Good that they are extinct now but our scientists all over the world have managed to learn quite a bit about them by studying their fossils.

The question is, how much do you know about these terror birds? Time to find out!

Which geological era did the terror birds live in?

Correct! Wrong!

The terror birds lived during the Cenozoic Era which came after the Mesozoic Era.

When did the terror birds live?

Correct! Wrong!

The terror birds came into existence after the dinosaurs were wiped out from the Earth. So, dinosaurs predate the terror birds.

What is the accepted temporal range of terror birds?

Correct! Wrong!

The accepted temporal range of terror birds is 62 million years ago to 1.8 million years ago.

What did the terror birds eat?

Correct! Wrong!

Terror birds were carnivores and they used to thrive only on meat.

When they lived, the terror birds were largest species of apex predators in their area. Where did they live?

Correct! Wrong!

The terror birds were the apex predators of South America.

What was one of the primary reasons for the extinction of the terror birds?

Correct! Wrong!

One of the major reasons for the extinction of the terror birds is ‘increased competition for food.’ During the Miocene and early Pliocene epochs of the Neogene period of Cenozoic era, there was an increase in population of the terror birds in South America. This suggested that food was abundant and the terror birds as predators, flourished. However, some 2.7 million years ago with the emergence of the Isthmus of Panama, North American predators like cats, bears, carnivorous dogs etc. managed to enter South America, thereby increasing the competition for food, leading to gradual decline in terror birds’ population. This population decrease caused by increased competition for food eventually became the major reason for the extinction of terror birds.

Which family do the terror birds belong to?

Correct! Wrong!

The terror birds belonged to the family ‘Phorusrhacidae’.

Terror birds were flightless birds.

Correct! Wrong!

True! The terror birds were all flightless birds.

Terror birds preyed mostly on large animals or small animals?

Correct! Wrong!

Terror birds usually preyed on small animals. However, that doesn’t mean that they did not prey on large animals. They usually preyed on small animals about the size of rabbits. Some scientists say that the birds used to prey on small animals because of the beak proportions. According to them, the jaw was not able to produce great amounts of bite force required to kill large preys. Their beaks on the other hand had bones that were tightly fused together. The fused bones made their beaks far more resilient to force in the front to back direction, which meant that these terror birds were capable of inflicting a great deal of damage by simply pecking instead of side-to-side head movements such as shaking the prey. In general, it is believed that these terror birds would first use their feet to first kick and injure their prey and then dispatch them by pecking. This however doesn’t rule out that they also hunted larger prey in the same fashion, that is, first kick them and peck them and then destroy their vital organs by using their beaks as a blade.

What was the locomotion style of the terror birds?

Correct! Wrong!

The terror birds were either slow walkers or agile and fast runners depending on their size and build. For instance, B. burmeisteri – a species of terror bird of genus Brontornis was 350 to 400 kgs with shorter lower leg bones. This particular species of terror birds were perhaps slow-moving ambush predators. Conversely, the lighter and agile Phorusrhacos (genus) were capable of running faster and most probably ran down their prey.

In terms of scientific classification of terror birds, there is one ‘family’, one ‘superfamily’ and several ‘subfamilies’. How many ‘subfamilies’ are there?

Correct! Wrong!

In total, there are 5 subfamilies of terror birds. They are: ‘Brontornithinae’; ‘Mesembriornithinae’; ‘Patagornithinae’; ‘Phorusrhacinae’ and ‘Psilopterinae’.

Of all the subfamilies, the terror birds of which subfamily were the smallest?

Correct! Wrong!

Terror birds belonging to the subfamily Psilopterinae were the smallest of all. The terror birds of this particular subfamily were only 70-100 centimeters or 2.3 to 3.3 feet in height (in standing position).

Terror birds of which subfamily were the biggest in terms of total weight?

Correct! Wrong!

The terror birds belonging to Brontornithinae subfamily were biggest in terms of total weight. For instance, B. burmeisteri belonging to Brontornis genus of subfamily Brontornithinae weighed around 350 to 400 kilograms. They were gigantic. They had a height of 7.5 feet or 2.3 meters.

Terror birds of which subfamily were biggest in terms of height?

Correct! Wrong!

Terror birds belonging to the subfamily Phorusrhacinae were the biggest in terms of height. They would stand up to 10 feet tall. However, they were slender and quicker than the terror birds belonging to the Brontornithinae subfamily.

Only one genus of terror birds from the subfamily Phorusrhacinae managed to move out of South America and reach North America during the Great American Interchange. Which genus was it?

Correct! Wrong!

The genus of terror birds that managed to reach North America during the Great American Interchange was Titanis. As a matter of fact, the northward migration of Titanis began some 5 million years ago perhaps because of the falling sea levels that revealed a path of island stepping-stones across the ocean gap that eventually became the Isthmus of Panama.

Which particular genus of terror birds was previously considered to be the youngest and the last of the terror birds to live on Earth?

Correct! Wrong!

Titanis was previously thought to be the youngest and the last of the terror birds. However, Titanis lived during the Early Pliocene to Early Pleistocene. Later, another phorusrhacid bird was discovered which lived during Late Pleistocene. It lived in South America and never managed to reach North America.

When did the Titanis become extinct?

Correct! Wrong!

The Titanis became extinct some 1.8 million years ago. However, before becoming extinct, they survived in North America for about 3 million years and coexisted with various big cats (such as Xenosmilus) and large canids.

The phorusrhacids or the terror birds hunted which habitat?

Correct! Wrong!

The terror birds hunted mostly in the open plains. The forested habitats were mostly taken by predatory marsupial of the order sparassodonts.

The phorusrhacids or the terror birds did not have well-developed necks.

Correct! Wrong!

False! The terror birds had very well-developed necks that supported their heavy heads. The neck of a phorusrhacid was very flexible and allowed to the terror bird to strike with terrifying power and speed. More interestingly, the neck actually looked short externally but the terror bird could easily expand its neck beyond the expected reach. This allowed the predatory bird to intimidate the prey and at the same time, deliver a fatal blow to the prey.

For how long did the terror birds live as a group?

Correct! Wrong!

Terror birds came into existence some 62 million years ago and went extinct some 1.8 million years ago (the accepted temporal range). This means, that they existed for some 60.2 million years as a group. This made them one of the most successful groups of animals to have lived on Earth during the prehistoric times.

Terror Birds
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