Continuoolithus
... that a tiny embryonic skeleton found inside the fossil dinosaur egg Continuoolithus died approximately 8 to 10 days into development, making it the youngest fossil vertebrate ever discovered?
... that a tiny embryonic skeleton found inside the fossil <a href="./Dinosaur_egg" id="mwBuk" rel="mw:WikiLink" title="Dinosaur egg">dinosaur egg</a> <i id="mwBuo"><b id="mwBus"><a href="./Continuoolithus" id="mwBuw" rel="mw:WikiLink" title="Continuoolithus">Continuoolithus</a></b></i> died approximately 8 to 10 days into development, making it the youngest fossil vertebrate ever discovered?