Ho-ly crap I missed that too.
Please please please seperate them immediately.
Even if your older dragon has not shown any violence yet, trust me, it IS coming.
Dragons of the same size and age can be incredibly territorial and violent to wards one another, but a baby will be viewed as nothing more than an irratation which is quickly rectifiable with a bite.
In the wild dragons will often eat smaller species of dragon as a snack.
I want you to have a look at this thread:
viewtopic.php?f=5&t=99997&hilit=+bitten
It shows EXACTLY what is going on here. An adult with a youngster. Happy one minute. Dead the next.
As other members have stressed beardies are
solitary and
territorial creatures and so should always be housed alone.
It is one of the most frustrating thing as a dragon lover that ignorant pet stores insist that this is acceptable. It sends people off with utterly false information which can end horrifically for the dragons, or end the owner up with a whacking great extra spend on a whole new set of equipment.
Unfortunatly you only need a liscence to sell reptiles. You do not need any special training or education to run a reptile store.
SOME reptiles can happily co-habit, however most store lack the in depth knowledge to understand that this is not the case for bearded dragons.
Beardies can and do attack eachother, and unfortunatly dragons are not like dogs, who can be taught about naughty aggressive behaviour. They can live in apparent harmony for months and then one day snap and thats it.
Dragons will think nothing of nipping off a chunk or tail/toe in order to defend their basking spot, unfortunatly it is just in their nature.
As soon as that baby annoys your adult he is going to be seriously injured.
I want you to show you what does happen:
In my time keeping dragons I have rescued three dragons who were living in a viv with other dragons.
This is Dexter. Rescued as an adult.
Dex was small for her age and was missing a bit of her tail, most of her right arm, most of her right foot and alot of her toes.
This is Ruben. Rescued at two months old.
Ruben had his leg and arms ripped off at the joints by his clutchmates.
This is Miso. Rescued at
only 3 weeks old
Little Miso, already has a tail nip and is missing most of her back toes.
And these were housed with dragons of similar age.
Asside from the violence your baby must be under the most incredible amount of stress being housed with an adult.
Stress will hinder her development and lead to a very sickly dragon, who may not grow at all.
I cannot stress this enough. Dragons are not to be housed together at the best of times, but a baby and adult is, in my mind, cruelty.
Please take him out of there now and keep him in a seperate tub with a heat lamp untill you can set up a proper enclosure for him.
Holly
Indeed, I must second mischa's caution here. There is extreme risk associated with housing more than one dragon in an enclosure, and the risk is even more serious with an adult and young dragon together. Are you planning to separate them? 
