I was able to get this with both my accounts. I was surprised I was able to get this with my level 20-21 team but managed to do it with 20 Marsupial Lion, 20 Thylacotator, 21 Monolorhino and 21 Trykosaurus, no boosts. I only had one death too. Funny, cause I had 2 deaths with 29 Ardentismaxima, 27 Thoradolosaurus and 27 Trykosaurus with boosts applied.
When you have a team of lower weaker creatures, you sit and strategise a bit more before committing to a battle.