The egg of a large modern bird is a very large cell, not the largest possible biological cell since there are very long nerves in squid, but it's likely the most massive modern cell.

But, what about the cells of prehistory? Many dinosaurs were far larger than modern birds, but I had trouble finding information on just how large their eggs could be. I was also surprised that the eggs were not bigger than those of modern birds. It seems the ratio of egg size to dinosaur size was much smaller... or has that even been studied?

Maybe the large eggs were all destroyed?

  • 2
    $\begingroup$ I was also surprised that the eggs were not bigger than those of modern birds. It seems the ratio of egg size to dinosaur size was much smaller. - where have you read this? $\endgroup$
    – rg255
    Jan 2 '16 at 18:52
  • $\begingroup$ I suppose that you define "large" in terms of volume. Note that there will have some issue of definition about what a cell is when you consider cases where cells of an entire tissue vanished to end up with more or less a big single cell with many nucleus. $\endgroup$
    – Remi.b
    Jan 2 '16 at 19:22
  • $\begingroup$ I didn't read it. It's an observation I'm having a hard time confirming or invalidating. Let's just use mass for largest. Volume is confusing. $\endgroup$
    – futurebird
    Jan 2 '16 at 23:12

The biggest known egg was laid by Aepyornis, the so-called Madagascan "elephant bird." See this short video. Of course, the eggs of most dinosaurs are unknown, so there could be something more massive waiting to be discovered. But the eggs of species much bigger than Aepyornis have been discovered, and the eggs just don't measure up to Madagascar's champion.

I'm not an expert on dinosaur eggs, but if you're looking for information, try searching for Protoceratops and Maiasaura peeblesorum. Protoceratops is a ceratopsian, ancestral to the more familiar Triceratops, whose remains are abundant in Mongolia. I believe many Protoceratops eggs have been discovered. (See At Last, A True Protoceratops Nest)

Maiasaura is a duck-billed dinosaur (hadrosaur) that left numerous fossils in what is now Montana. The fossils include some fabulous remains of nurseries (e.g. Egg Mountain). (See Maiasaura)

These links may not feature any information about egg size, but they should at least give you some background information. I'm sure Dr. John Horner has commented on the size of Maiasaura eggs somewhere. He's written on a wide variety of topics, including dinosaur growth rates, physiology, etc.

P.S. Here's a cool link. There's a photo of a fossilized Maiasaura embryo emerging from its egg (#4, I think). Another page (8?) claims that no dinosaur egg could be more than two feet in diameter.


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