Helodus placenta
Newberry & Worthen, 1866
Classification: Holocephali Helodontiformes Helodontidae
	Reference of the original description
	
	
Descriptions of new species of vertebrates, mainly from the Sub-Carboniferous Limestome and Coal Measures of Illinois. Geological Survey of Illinois, 2, 9–134
Descriptions of new species of vertebrates, mainly from the Sub-Carboniferous Limestome and Coal Measures of Illinois. Geological Survey of Illinois, 2, 9–134
	Types
Helodus placenta
	
	
	
Helodus placenta
Description:
Citation: Helodus placenta Newberry & Worthen, 1866: In: Database of fossil elasmobranch teeth www.shark-references.com, World Wide Web electronic publication, Version 11/2025
		Remarks
shark-references Species-ID=13596;
		
		shark-references Species-ID=13596;
		References
		
	
		
		
			
Rise and diversification of chondrichthyans in the Paleozoic. Paleobiology, 50(2), 271–284
DOI: 10.1017/pab.2024.1
	
	
		
		
			
Descriptions of new species of vertebrates, mainly from the Sub-Carboniferous Limestome and Coal Measures of Illinois. Geological Survey of Illinois, 2, 9–134
	
	
Rise and diversification of chondrichthyans in the Paleozoic. Paleobiology, 50(2), 271–284
DOI: 10.1017/pab.2024.1

Descriptions of new species of vertebrates, mainly from the Sub-Carboniferous Limestome and Coal Measures of Illinois. Geological Survey of Illinois, 2, 9–134
				
				
    					
    					
    					
    					
                        
    					








