Placental mammals DNA

Project: (P561) Morphological and molecular evidence
converge upon a robust phylogeny of the
megadiverse Holometabola
Image Morphobank

BBC Science and Environment James Palmer reports on recent advances in the research on the evolutionary origins of placental mammals

Placental mammals - as opposed to the kind that lay eggs, such as the platypus, or carry young in pouches, such as the kangaroo - are an extraordinarily diverse group of animals with more than 5,000 species today. They include examples that fly, swim and run, and range in weight from a couple of grams to hundreds of tonnes.

A wealth of fossil evidence had pointed to the notion that the group, or clade, grew in an "explosion" of species shortly after the dinosaurs' end about 65 million years ago.

But a range of genetic studies that look for fairly regular changes in genetic makeup suggested that the group arose as long as 100 million years ago, with mammals such as early rodents sharing the Earth with the dinosaurs.
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To build the database, the team gathered more than 4,500 details of phenotype - diet, lengths of limbs, shapes of teeth, length of fur if any, and so on - from 86 different species that are around today, and from 40 fossils of extinct animals.

To that they added some 12,000 detailed images and genetic information for all of the current species, putting all the data into what Dr O'Leary called "a supermatrix - essentially like a spreadsheet, filled with observations and images, to create a really rich description of mammals we'd sampled".

"That really wasn't possible until we developed this software called Morphobank. Our experts in China or Brazil or Canada or the US or just across the hall could all be working in one place at the same time," Dr O'Leary said.

Read the entire article in BBC News Science and Environment