'A completely different story': 300 million-year-old fossils reveal the first vertebrate land dwellers weren't what we thought, researchers claim
Researchers studying fossils from Mazon Creek, Illinois, found that early tetrapods did not undergo an amphibian-like metamorphosis. These baby embolomeres, which were crocodile-like predators, suggest a different evolutionary path for the ancestors of mammals, birds, and reptiles. The discovery stems from a specimen originally mislabeled as a baby lamprey.
What changed
New evidence from baby embolomere fossils suggests early land vertebrates lacked a larval stage with external gills.
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300-Million-Year-Old Fossils Challenge Early Land Vertebrate Evolution
confidence 100%Researchers studying fossils from Mazon Creek, Illinois, found that early tetrapods did not undergo an amphibian-like metamorphosis. These baby embolomeres, which were crocodile-like predators, suggest a different evolutionary path for the ancestors of mammals, birds, and reptiles. The discovery stems from a specimen originally mislabeled as a baby lamprey.
What's confirmed:
- Fossils of baby embolomeres were discovered in Mazon Creek, Illinois.
- Embolomeres were crocodile-like predators that lived between 350 and 280 million years ago.
- The fossils indicate early tetrapods did not use an amphibian-like metamorphosis to evolve for land dwelling.
- Early ancestors of mammals, birds, and reptiles did not have a larval stage with external gills like modern salamanders or frogs.
- One of the fossils was initially mislabeled as a baby lamprey.