Ostriches & Emu are different birds

An ostrich lives in Africa, doesn't have feathers on its neck (maybe), and when fully grown average in at around 7 ft. I think they run faster, and people can ride them. Emus live in Australia, have feathers everywhere except their legs and other places, average in at 5.5 feet, run at 55mph on average, and have won a war against Australia in 1932. Emus are second largest bird in the world and also, the largest bird native to Australia and whereas, Ostrich is the largest bird in the world by height and a native of Africa.

Emus will have deep brown feathers and so, it will be very difficult to differentiate between the male and female spices. But, whereas, in ostriches, both male and female birds will have different features. The male ostriches have black feathers with white on the wings and whereas the female ones will have grey brown feathers. Emus are having strong legs with three toes which allows it to run at a speed of up to 30mph.

Their feet are said to be strong enough to kill a human. The ostriches are having extremely strong legs with two toes that are designed in a manner to enable it to run at speeds of up to 40mph. The ostrich also has exceptionally large eyes in relation to their heads. In fact they are said to have the large eyes in land vertebrates. Ostriches (left) and emus (right) are both members of the ratite family, a group of large, flightless birds that are scattered throughout the Southern Hemisphere, including Africa (the ostrich’s range) and Australia (the emu’s range).

They share many physical characteristics, such as the broad eyes; the elongated, featherless neck; the long, strong legs that burst into explosive speeds when on the run; the long, dagger-like claws at the end of their feet – which they use vigorously to defend themselves –; the underdeveloped breast muscles; the retrogressed flight feathers; the prominent wings that are used not for flight but for courtship; etc… Additionally, the males and the females in both species are polygamous, and their eggs’ shells have a thickness so great that the hatchlings develop more rapidly than any other bird.

But the two birds also have differences in terms of size, ecology and behavior: although emus are the largest birds in Australia (around 36–40 kg), they remain small when compared to a fully grown ostrich, the largest bird on earth (around 100–120 kg), and they’re mostly omnivores – feeding on plants as well as invertebrates like spiders and scorpions –, while ostriches tend to develop a strictly herbivorous diet (though, occasionally, they may eat insects).

Moreover, emus have three toes on their feet (see above), in contrast with ostriches that possess only two toes, as well as a long tendon that allows them to run at around 55–70 km/h; whereas emus can only make it to 48 km/h. Lastly, the emu is sometimes considered more docile towards humans than the ostrich (see below). But still, despite their differences, emus and ostriches do have similarities, and so they remain closely related to each other, since they are flightless birds that are part of the ratite order as mentioned earlier. Which practically makes them cousins as you correctly guessed.

Emus & ostriches have many things in common but are also quite different. Both are large birds — the ostrich is the largest & the emu the second largest. Both are ancient, dating back to the Cretaceous period (60–140 million years ago) when dinosaurs roamed the Earth. Both belong to a group of birds called ratites, which refers to the flat sternum (rather than a keel-like sternum) — both are flightless & hence do not have strong flight muscles that anchor on the sternum.

Differences include size, appearance, anatomy & physiology, geography, dietary needs, reproduction & many other characteristics. The previous answer mentions some of these & provides nice photos of a male ostrich (females are not as colorful) & an emu (males & females look almost identical). I would strongly urge you to look on the internet where there are multiple references that address your question. One aspect that is not mentioned too often relates to social interactions.

Keep in mind that birds of both specials are large, run fast & can be formidable foes, which can inflict serious & even life-threatening injuries. Emus as a rule are curious & shy. They tend to avoid human contact & will only become aggressive when they feel threatened. They can be tamed with relative ease & make surprisingly lovable pets. They learn their name, come when called & enjoy being fed, petted & hugged. The ostrich is a different bird. Less social. curious but assertive, more aggressive & certainly dangerous. Taming an ostrich is a difficult task (some say impossible).

As per my understanding they didn’t lose the ability ! but you can say they didn’t get that ability. As we all know birds are form Dino and if you imagine you can see there are several steps to become a bird form Dino. But you need to loose weight, you need to be aerodynamic, you need to have some type of flap / wing etc. There are several others also.

Also now few of these worked well for a group and they get feather and wings and they can fly. And a few didn’t get proper feathers but still manage to fly (Pterosaurs!)-not a bird!. Now some how flight and flightless both clicked(survived!) but 1st one is more successful than second one. Thus you can see both together. There is no rule in evolution that only one will win. If both /several potential all will win. Check the plant kingdom! so many winners together! some are continuing form Dino time! Cheers!