Giraffe Evolution

I’ve known for some time that giraffes and okapi are related. But in looking up giraffe evolution, I’ve discovered that giraffes are also (distantly) related to pronghorns, deer, musk deer, cattle, goats, sheep, wildebeests, and antelope. What a wide-ranging family! However, the opaki are their closest relative, so close that a 7-million year old fossil had a neck that was a blending of a giraffe neck and an opaki neck.

Giraffe and opaki ancestors once roamed all of Eurasia, but in modern times, they are only found in Africa. Giraffes live in the savanna grasslands, while okapi live in the rain forest.

One possible early ancestor of giraffes is the Canthumeryx, which lived in Libya. No one is sure when it lived; guesses range from 25 million years ago to 14.3 million years ago. It was a medium-sized animal, slender and antelope-like.

About 15 million years ago, Giraffokeryx appeared in the Indian subcontinent. It may have resembled an okapi or a small giraffe. It showed some definite lengthening of the neck.

The Sivatherium ranged throughout Africa and to the Indian subcontinent about 1 million years ago, and may have gone extinct as recently at 8,000 years ago, as ancient rock paintings greatly resemble them. The picture of a reconstruction of one show a pair of horns that look rather like the horns of a Texas longhorn, but only about a foot long each. The neck wasn’t as long as a modern giraffe, and the spots are depicted as being not quite so regular. It stood 7.2 feet tall at the shoulder, with a total height of 9.8 ft and a body weight of up to half a ton. Its shoulders were very strong to support the neck muscles required to life the heavy skull.

There was another giraffe-type animal that ranged from India to Turkey called the Bramatherium, which was closely related to the Sivatherium.

The Shansitherium was a superficially moose- or antelope-like giraffe from the Shanxi province in China. They were closely related to the Samotherium, which was rather like a half-way point between a giraffe and an opaki, as far as size goes.

Giraffes have horns! They are actually called ossicones, being made of bone and covered in furry skin. Some of their ancestors had 2, like modern giraffes, and some had 4. Sometimes they stuck up, or stuck up and curved back, or maybe they stuck out vertically. The Sivatherium horns as I described looked like small longhorns, did not look to be covered in furry skin, but they also had a pair of ossicones above their eyes.

So, if I ever want to make up a giraffe-like alien creature, I now know there is plenty of leeway for using my imagination!

https://evolution-institute.org/how-giraffes-evolved-such-a-large-neck/

https://en.wikipedia.org/wiki/Giraffidae

Extinction Event 1

We all know the dinosaurs went extinct. Okay, most of them. But that was not the first ‘Great Extinction Event that Earth has suffered. Since I’m really only aware of that one and its possible cause, I decided to investigate the first one, just to see what I could find. Apparently, it was caused by oxygen!

I know, right? Something we think is a good thing, yet it caused a massive die-off! How could this be? Let’s take a look.

First, let’s be sure we understand what an extinction event is; it is a widespread and rapid decrease in the biodiversity on Earth. Estimates of how many extinction events we’ve already had range from 5 to as many as 20.

Most life on Earth is microbial and thus difficult to measure. Therefore recorded extinction events are those that affected the easily observed, biologically-complex component of life on Earth. Normally, extinction of various lifeforms occur at an uneven rate. An Extinction Event is when a lot of different lifeforms go extinct at pretty much the same time.

The Oxygenation Crisis occurred around 2.45 billion years ago, but technically, as I studied it further, it is not considered one of The Great Extinction Events. Maybe because it’s hard to find fossils from that long ago, so they can’t be sure what died off and in what numbers, but it was big enough that the fossils they have found indicate something happened.

From what I understand, Earth’s atmosphere at the time had next to no free oxygen in it. But then photosynthesizing cyanobacteria (which some call blue-green algae) evolved in the shallow sea that covered most of Earth. The cyanobacteria did what it does, and in the process, released free oxygen into the water. Eventually, the water couldn’t hold any more of it and released free oxygen into the air. All this free oxygen (which was a mere pittance compared to what we currently have in our atmosphere) played havoc with the metabolism of most of the living organisms at the time and a great deal of them died.

And the cyanobacteria continued putting out more oxygen.

Which opened the gates for more complex biolife forms.

So, extinction events are not always a bad thing... if you aren’t a species that is going extinct. But they do tend to create ‘bottle-necks’ of survival, which are followed by much evolving and diversification to fill all the empty niches that result.

https://en.wikipedia.org/wiki/Extinction_event

Dinosaurs

Like most kids, I had a steady interest in dinosaurs when I was young. I never truly outgrew that interest, and the science magazines I read don’t have much to report on them very often. How disappointing. I long to learn all the new stuff they’ve learned since I was a kid. Can you imagine my surprise a few decades ago when I discovered Fred Flintstone’s powerhouse Brontosaurus never actually existed? It was the result of a few bones that did not necessarily belong together and a scientist’s active imagination while trying to put them together.

One of my school science projects was on dinosaurs. I bought several giant bars of Ivory soap and tried to carve them into various dinosaurs. The T-Rex didn’t want to stand up, the stegasaurus’ back plates were difficult to carve without breaking them off. The easiest to carve was the brontosaurus, which way back then still had a place on the dinosaur family tree.

I can’t do justice to dinosaurs in a few hundred words. After all, they were around - in one form or another - for millions of years. So I plan to look around, pick some interesting versions and report on them over the course of several months.

What do you think you know about dinosaurs? Were they all cold-blooded? Covered in reptile scales or simply skin similar to our own? Did they do any parenting of their young, or simply lay their eggs and move on through the countryside? Did they really evolve into birds? How big did they get? What was their smallest representative? Are there any ‘dinosaurs’ alive today, or maybe animals that look very similar to their ancient ancestors?

I remember a story - I don’t remember if I saw it visually or read it - where a group of hadrosaurs (That’s what I remember their type being, but I may be completely wrong.) had left Earth in some fashion back in the Long Ago, and established a home on another planet in another system. And now their descendants were space travelers and meeting humans in the vastness of space.

Wouldn’t that be something?

Well, since we’re approaching that point where we may be space traveling in a few generations (meaning, outside our home system), maybe we should be considering what evolved dinosaurs might be like. And to do that, we should start by learning what dinosaurs were actually like.

Any suggestions you want me to look at?