Pregnant fossil shows whales first walked on land before sea

[wautd]

For those who doubted that whale ancestors originally came from land

FOSSILS from two early whales, a male and a rare pregnant female, have shed light on how whales made the leap from walking on land to ruling the sea.
The fetal remains, found with the 47.5 million-year-old pregnant female, were positioned head down, suggesting these creatures gave birth on land, while spending much of the rest of their time in the water.

Initially, the tiny fetal teeth stumped University of Michigan paleontologist Philip Gingerich, whose team discovered the fossils in Pakistan in 2000 and 2004.

"When I first saw the small teeth in the field, I thought we were dealing with a small adult whale, but then we continued to expose the specimen and found ribs that seemed too large to go with those teeth," Dr Gingerich, whose study appears in the Public Library of Science journal PLoS ONE.

The fetal skeleton is the first specimen of the extinct whale group known as Archaeoceti, and the find represents a new species named Maiacetus inuus, a hybrid of the words for "mother whale" and Inuus, the name of a Roman fertility god.

The fetus was positioned head down like other land animals suggesting the group had not yet made the leap to giving birth in the water like modern whales - which are born tail first to allow them to start swimming right after birth.

The 2.59-metre male, which was collected in the same fossil beds as the female, is about 12 per cent bigger and had fangs that were 20 per cent larger than those of the female. Dr Gingerich said these well developed choppers suggest the creatures spent a large portion of their time catching and eating fish.

Both fossils had four flipper-like legs that could have supported their weight on land, but only for short distances, suggesting these whales likely came on shore to mate, rest and give birth, Dr Gingerich said.

"They clearly were tied to shore," Gingerich said. "They were living at the land-sea interface and going back and forth."

He said the Maiacetus fossils appear to represent an intermediate whale form, showing the evolution from land-dwelling to aquatic creatures.

The full study can be found at http://dx.plos.org/10.1371/journal.pone.0004366

[Serafina]

Nice - yet another "transistion" fossile. More proof for evolution, yay .

Of course, creationists now have two new gaps for scientists to fill

[Surlethe]

Hmm, at that point in their evolution, it sounds like whales had more in common with walruses and seals than modern cetaceans. It's a nice reminder that modern species are not static -- more likely than not (if we give them the chance) these modern land-water interface species will end up as totally aquatic. In a few dozen million years, that is.

[Kitsune]

The PDF article in the link is definitely worth downloading

[Rye]

Hmm, at that point in their evolution, it sounds like whales had more in common with walruses and seals than modern cetaceans. It's a nice reminder that modern species are not static -- more likely than not (if we give them the chance) these modern land-water interface species will end up as totally aquatic. In a few dozen million years, that is.

The closest living relative to the whale is apparently the hippo, which explains a lot.

[OsirisLord]

I never doubted it. Whales are mammals, and the first mammals to appear in the fossil record were land dwellers so it's only logical that the ancestors of whales should have walked on land at some point. We don't really need solid fossil evidence to make this claim any more credible.

And then we found Ambelocetus. But this is still a really cool fossil. I wish they had included a picture of it.

[Kitsune]

As I stated, check out the PDF article then:
http://www.plosone.org/article/fetchObj ... tation=PDF

Has some nice pictures and photos

[Illuminatus Primus]

Hmm, at that point in their evolution, it sounds like whales had more in common with walruses and seals than modern cetaceans. It's a nice reminder that modern species are not static -- more likely than not (if we give them the chance) these modern land-water interface species will end up as totally aquatic. In a few dozen million years, that is.

Well I always figured a big reason for the transition was the niche left behind by the die-out of the large aquatic reptiles of the Mesozoic.

[Drooling Iguana]

Hmm, at that point in their evolution, it sounds like whales had more in common with walruses and seals than modern cetaceans. It's a nice reminder that modern species are not static -- more likely than not (if we give them the chance) these modern land-water interface species will end up as totally aquatic. In a few dozen million years, that is.

If they did, they'd encounter fierce competition from the whales (assuming we haven't killed all of them by then) who've had a lot longer to adapt to their environment.

[LadyTevar]

Hmm, at that point in their evolution, it sounds like whales had more in common with walruses and seals than modern cetaceans. It's a nice reminder that modern species are not static -- more likely than not (if we give them the chance) these modern land-water interface species will end up as totally aquatic. In a few dozen million years, that is.

If they did, they'd encounter fierce competition from the whales (assuming we haven't killed all of them by then) who've had a lot longer to adapt to their environment.

True, but many whale species have also had a unnatural die-back due to human hunting.

[Alyrium Denryle]

Hmm, at that point in their evolution, it sounds like whales had more in common with walruses and seals than modern cetaceans. It's a nice reminder that modern species are not static -- more likely than not (if we give them the chance) these modern land-water interface species will end up as totally aquatic. In a few dozen million years, that is.

If they did, they'd encounter fierce competition from the whales (assuming we haven't killed all of them by then) who've had a lot longer to adapt to their environment.

True, but many whale species have also had a unnatural die-back due to human hunting.

There are still a lot of fully aquatic niches that are not filled, especially in coastal and estuarine environments...

[Surlethe]

Split contentless post.

[Big Orange]

There is some contention that the land dwelling elephants had early ancestors who were more amphibious than their descendents, in the way modern elephants snorkle with their trunks when submerging into deep bodies of water (and they're one of the candidates who could evolve into being similar to modern whales).