Let me expand on my comment...
There are several such clocks, there are a couple of methods in use.
The oldest and primary methodology is to look at the bodies of the plants and animals and assemble the evolutionary tree by how closely these animals resemble each other (taxonomy). There are several authoritative databases on this data. The encyclopedia of life is a major aggregator for taxonomic analysis. They are tied into the Integrated Taxonomic Information system (ITIS). The millions of species known have not been sequenced and this is probably the most comprehensive overview of life as we know it on earth. The ITIS data is downloadable.
On the other hand the taxonomic record has many known problems. For example Rodentia (rodents) are known to be a bit of a dumping ground where hard to classify mammals are put because we just don't really know where they go.
In cases where there is money and energy to resolve an issue like this, a main methodology to gauge the evolutionary distance is to observe the number of mutations that appear in genomic dna over time. Their sequence divergence varies over time at varying rates, but overall that's the clock. This is pretty indisputable, but the coverage over the phylogenetic tree is low. There are a few databases focused on bacteria for instance and fungi, but you have to know what you are looking for. Often such evidence is entered into databases such as ITIS over time.