In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Ethinyl estradiol - treated animals excreted significantly less 14C as taurocholic acid than did control animals , consistent with an impairment of 7alpha - hydroxylation of taurodeoxycholic acid .
### Output Text:
<span class="chemical">Ethinyl estradiol</span> - treated animals excreted significantly less 14C as <span class="chemical">taurocholic acid</span> than did control animals , consistent with an impairment of 7alpha - hydroxylation of <span class="chemical">taurodeoxycholic acid</span> . 